Brazed diamond tools and methods for making the same

ABSTRACT

Superabrasive tools and methods for the making thereof are disclosed and described. In one aspect, superabrasive particles are chemically bonded to a matrix support material according to a predetermined pattern by a braze alloy. The brazing alloy may be provided as a powder, thin sheet, or sheet of amorphous alloy. A template having a plurality of apertures arranged in a predetermined pattern may be used to place the superabrasive particles on a given substrate or matrix support material.

PRIORITY DATA

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/463,897, filed on May 11, 2009, which is a continuation ofU.S. patent application Ser. No. 11/818,894, filed on Jun. 14, 2007,which is a continuation of U.S. patent application Ser. No. 10/791,300,filed Mar. 1, 2004, now issued as U.S. Pat. No. 7,323,049, which is acontinuation-in-part of U.S. patent application Ser. No. 10/259,168,filed Sep. 27, 2002, now issued as U.S. Pat. No. 7,124,753, which is acontinuation-in-part of U.S. patent application Ser. No. 09/935,204,filed Aug. 22, 2001, now issued as U.S. Pat. No. 6,679,243, and of U.S.patent application Ser. No. 10/109,531, filed Mar. 27, 2002, now issuedas U.S. Pat. No. 6,884,155. U.S. Pat. No. 6,679,243 is acontinuation-in-part of U.S. patent application Ser. No. 08/835,117,filed on Apr. 4, 1997 and a continuation-in-part of U.S. patentapplication Ser. No. 09/399,573, filed Sep. 20, 1999, now issued as U.S.Pat. No. 6,286,498, which is a continuation-in-part of U.S. patentapplication Ser. No. 08/832,852, filed Apr. 4, 1997, now abandoned. U.S.Pat. No. 6,884,155 is a continuation-in-part of U.S. patent applicationSer. No. 09/558,582, filed Apr. 26, 2000, now issued as U.S. Pat. No.6,368,198, which is a continuation-in-part of U.S. patent applicationSer. No. 09/447,620, filed Nov. 22, 1999, now abandoned, all of whichare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to tools having diamondparticles chemically bonded to a matrix support material, or asubstrate, and arranged in a predetermined pattern. Accordingly, thepresent invention involves the fields of chemistry, metallurgy, andmaterials science.

BACKGROUND OF THE INVENTION

Abrasive tools have long been used in numerous applications, includingcutting, drilling, sawing, grinding, lapping and polishing of materials.Because diamond is the hardest abrasive material currently known, it iswidely used as a superabrasive on saws, drills, and other devices, whichutilize the abrasive to cut, form, or polish other hard materials.

Diamond tools are particularly indispensable for applications whereother tools lack the hardness and durability to be commerciallypractical. For example, in the stone industry, where rocks are cut,drilled, and sawed, diamond tools are about the only tools that aresufficiently hard and durable to make the cutting, etc., economical. Ifdiamond tools were not used, many such industries would be economicallyinfeasible. Likewise, in the precision grinding industry, diamond tools,due to their superior wear resistance, are uniquely capable ofdeveloping the tight tolerances required, while simultaneouslywithstanding wear sufficiently to be practical.

A typical superabrasive tool, such as a diamond saw blade, ismanufactured by mixing diamond particles (e.g., 40/50 U.S. mesh sawgrit) with a suitable metal support matrix powder (e.g., cobalt powderof 1.5 micrometer in size). The mixture is then compressed in a mold toform the right shape (e.g., a saw segment). This “green” form of thetool is then consolidated by sintering at a temperature between700-1200° C. to form a single body with a plurality of abrasiveparticles disposed therein. Finally, the consolidated body is attached(e.g., by traditional brazing or soldering) to a tool body; such as theround blade of a saw, to form the final product.

Despite their prevailing use, diamond tools generally suffer fromseveral significant limitations, which place unnecessary limits on theiruseful life. For example, the abrasive diamond or cubic boron nitride(CBN) particles are not distributed uniformly in the matrix that holdsthem in place. As a result, the abrasive particles are not positioned tomaximize efficiency for cutting, drilling, grinding, polishing, etc.

The distance between diamond or CBN abrasive particles determines thework load each particle will perform. Improper spacing of the diamond orCBN abrasive particles typically leads to premature failure of theabrasive surface or structure. Thus, if the diamond/CBN abrasiveparticles are too close to one another, some of the particles areredundant and provide little or no assistance in cutting or grinding. Inaddition, excess particles add to the expense of production due the highcost of diamond and cubic boron nitride. Moreover, these non-performingdiamond or CBN particles can block the passage of debris, therebyreducing the cutting efficiency. Thus, having abrasive particlesdisposed too close to one another adds to the cost, while decreasing theuseful life of the tool.

On the other hand, if abrasive particles are spaced too far apart, theworkload (e.g., the impact force exerted by the work piece) for eachparticle becomes excessive. The sparsely distributed diamond or CBNabrasive particles may be crushed, or even dislodged from the matrixinto which they are disposed. The damaged or missing abrasive particlesare unable to fully assist in the workload. Thus, the workload istransferred to the surviving abrasive particles. The failure of eachabrasive particle causes a chain reaction which soon renders the toolineffective to cut, drill, grind, etc.

Different applications may require different size of diamond (or cubicboron nitride) abrasive particles. For example, drilling and sawingapplications may require a large sized (20 to 60 U.S. mesh) diamond gritto be used in the final tool. The metal substrate of the tool istypically selected from cobalt, nickel, iron, copper, bronze, alloysthereof, and/or mixtures thereof. For grinding applications, a smallsized (60/400 U.S. mesh) diamond grit (or cubic boron nitride) is mixedwith either metal (typically bronze), ceramic/glass (typically a mixtureof oxides of sodium, potassium, silicon, and aluminum) or resin(typically phenolic).

Often the tool may include a matrix support material, such as a metalpowder, which holds or supports the diamond particles. However, becausediamond or cubic boron nitride is much larger than the matrix powder(300 times in the above example for making saw segments), and it is muchlighter than the latter (about ⅓ in density for making saw segments), itis very difficult to mix the two to achieve uniformity. Moreover, evenwhen the mixing is thorough, diamond particles can still segregate frommetal powder in the subsequent treatments such as pouring the mixtureinto a mold, or when the mixture is subjected to vibration. Thedistribution problem is particularly troublesome for making diamondtools when diamond is mixed in the metal support matrix.

There is yet another limitation associated with the many methods ofpositioning diamond grits in a tool. Many times a metal bond diamondtool requires different sizes of diamond grits and/or different diamondconcentrations to be disposed at different parts of the same diamondtool. For example, saw segments tend to wear faster on the edge or frontthan the middle. Therefore, higher concentrations and smaller diamondgrit are preferred in these locations to prevent uneven wear and thuspremature failure of the saw segment. These higher concentration/smallersize segments (i.e. “sandwich” segments) are difficult to fabricate bymixing diamond particles with metal powder. Thus, despite the knownadvantages of having varied diamond grit sizes and concentration levels,such configurations are seldom used because of the lack of a practicalmethod of making thereof.

Another drawback of many diamond tools is that the abrasive particles,or “grits” are insufficiently attached to the tool substrate, or matrixsupport material, to maximize useful life of the cutting, drilling,polishing, etc., body. In fact, in most cases, diamond grits are merelymechanically embedded in the matrix support material. As a result,diamond grits are often knocked off or pulled out prematurely. Moreover,the grit may receive inadequate mechanical support from the looselybonded matrix under work conditions. Hence, the diamond particles may beshattered by the impact of the tool against the workpiece to which theabrasive is applied.

It has been estimated that, in a typical diamond tool, less than aboutone tenth of the grit is actually consumed in the intended application(i.e. during actual cutting, drilling, polishing, etc). The remainder iswasted by either being leftover when the tool's useful life has expired,or by being pulled-out or broken during use due to poor attachment andinadequate support. Most of these diamond losses could be avoided if thediamond particles can be properly positioned in and firmly attached tothe surrounding matrix.

In order to maximize the mechanical hold on the diamond grits, they aregenerally buried deep in the substrate matrix. As a result, theprotrusion of the diamond particles above the tool surface is generallyless than desirable. Low grit protrusion limits the cutting height forbreaking the material to be cut. As a result, friction increases andlimits the cutting speed and life of the cutting tool.

In order to anchor diamond grit firmly in the support matrix, it ishighly desirable for the matrix to form carbide around the surface ofthe diamond. The chemical bond so formed is much stronger than thetraditional mechanical attachment. The carbide may be formed by reactingdiamond with suitable carbide formers such as a transition metal.Typical carbide forming transition metals are: titanium (Ti), vanadium(V), chromium (Cr), zirconium (Zr), molybdenum (Mo), and tungsten (W).

The formation of carbide requires that the carbide former be depositedaround the diamond and that the two subsequently be caused to react toform carbide. Moreover, the non-reacted carbide former must also beconsolidated by sintering or other means. All these steps requiretreatment at high temperatures. However, diamond may be degraded whenexposed to a temperature above about 1,000° C. The degradation is due toeither the reaction with the matrix material or the development ofmicro-cracks around metal inclusions inside the crystal. Theseinclusions are often trapped catalysts used in the formation ofsynthetic diamond.

Most carbide formers are refractory metals so they may not beconsolidated below a temperature of about 1,200° C. Hence, refractorycarbide formers are not suitable as the main constituent of the matrixsupport material.

There are, however, some carbide formers that may have a lower meltingtemperature, such as manganese (Mn), iron (Fe), silicon (Si), andaluminum (Al). However, these carbide formers may have other undesirableproperties that prohibit them from being used as the primary constituentof the matrix support material. For example, both manganese and iron areused as catalysts for synthesizing diamond at high pressure (above 50Kb). Hence, they can catalyze diamond back to graphite during thesintering of the matrix powder at a lower pressure. The back conversionis the main cause of diamond degradation at high temperature.

Aluminum, on the other hand, has a low melting point (660° C.), thus,making it easy to work with for securing the diamond particles. However,the melting point of aluminum can be approached when diamond grit iscutting aggressively. Hence, aluminum may become too soft to support thediamond grit during the cutting operation. Moreover, aluminum tends toform the carbide Al₄C₃ at the interface with diamond. This carbide iseasily hydrolyzed so it may be disintegrated when exposed to coolant.Hence, aluminum typically is not a suitable carbide former to bonddiamond in a matrix.

To avoid the high temperature of sintering, carbide formers, such astungsten, are often diluted as minor constituents in the matrix that ismade of primarily either Co or bronze. During the sintering process,there is a minimal amount, if any, of liquid phase formed. The diffusionof carbide former through a solid medium toward diamond is very slow. Asa result, the formation of carbide on the surface of diamond isnegligible. Therefore, by adding a carbide former as a minor matrixconstituent, the improvement of diamond attachment is marginal at best.

In order to ensure the formation of carbide on the surface of diamond,the carbide former may be coated onto the diamond before mixing with thematrix powder. In this way, the carbide former, although it may be aminor ingredient in the matrix, can be concentrated around diamond toform the desired bonding.

The coating of diamond may be applied chemically or physically. In theformer case, the coated metal is formed by a chemical reaction,generally at a relatively high temperature. For example, by mixingdiamond with carbide formers such as titanium or chromium, and heatingthe mixture under a vacuum or in a protective atmosphere, a thin layerof the carbide former may be deposited onto the diamond. Increasingtemperature may increase the thickness of the coating. The addition of asuitable gas (e.g. HCl vapor) that assists the transport of the metalmay also accelerate the deposition rate. Alternatively, the coating maybe performed in a molten salt.

In addition to sintering, infiltration is also a common technique formaking diamond tools; in particular for drill bits and other specialtydiamond tools that contain large (i.e. greater than U.S. mesh 30/40)diamond grit. Most commonly used infiltrants for these tools are copperbased alloys. These infiltrants must flow and penetrate the small poresin the matrix powder. In order to avoid the diamond degradation at hightemperature, the melting point of the infiltrant must be low. Hence, theinfiltrant often contains a low melting point constituent, such as zinc(Zn). In addition to lowering the melting point of the infiltrant, thelow melting point constituent also reduces the viscosity so theinfiltrant can flow with ease. However, as most carbide formers tend toincrease the melting point of the infiltrant, they are excluded frommost infiltrants. As a result, these infiltrants cannot improve thebonding of diamond.

One specific process that has become dependent on the use of diamondtools is chemical mechanical polishing (CMP). This process has becomestandard in the semi-conductor and computer industry for polishingwafers of ceramics, silicon, glass, quartz, etc. In general terms, thework piece to be polished is held against a spinning polishing pad ofpolyurethane, or other suitable material. The top of the pad holds aslurry of acid and abrasive particles, usually by a mechanism such asfibers, or small pores, which provide a friction force sufficient toprevent the particles from being thrown off of the pad due to thecentrifugal force exerted by the pad's spinning motion. Therefore, it isimportant to keep the top of the pad as flexible as possible, and tokeep the fibers as erect as possible, or to assure that there are anabundance of open and pores available to receive new abrasive particles.

A problem with maintaining the top of the pad is caused by anaccumulation of polishing debris coming from the work piece, abrasiveslurry, and polishing disk. This accumulation causes a “glazing” orhardening of the top of the pad, and significantly decreases the pad'soverall polishing performance. Therefore, attempts have been made torevive the top of the pad by “combing” or “cutting” it with variousdevices. This process has come to be known as “dressing” or“conditioning” the CMP pad. The device most widely used for pad dressingis a disk with a plurality of super hard crystalline particles, such asdiamond particles or cBN particles attached thereto.

Dressing disks made by conventional methods share several problems withother superabrasive tools, made by conventional methods. However, suchissues may have a much greater impact on the CMP process. For example,poor superabrasive grit retention may lead to scratching and ruining ofthe work piece. Uneven work loading of the superabrasive grits resultingfrom clustered or unevenly spaced particle groups may cause overdressingof certain pad areas and under dressing of others, which results inunsuitable work piece polishing. Moreover, when the superabrasiveparticles of dressing disks do not extend to a uniform height above thesubstrate surface of the disk uneven dressing of the CMP pad is furtherpropagated, because many particles from the dresser may not touch thepad.

In addition to the above-recited issues with particle retention anddistribution, the CMP pad dressing process itself creates additionalissues that make uncontrolled superabrasive particle placementunacceptable. For example, the downward pressing force of a dressingdisk on a CMP may depress the pad upon contact with the leading edge ofthe dresser, and prevent the remaining superabrasive particles on thepad dresser from sufficiently contacting the pad to achieve evendressing.

Warping of the pad dresser working surface during the brazing processalso often causes abrasive particles to dislodge. During the brazingprocess the pad dresser must be exposed to very high temperatures.Exposure to this extreme heat can cause the working surface of the paddresser to warp, thus compromising the smoothness and planarity of thepad dresser's working surface. As a result, the braze portion of theworking surface will be rough, having high and low spots. Such spots areundesirable, as they may cause the braze to begin flaking off, andmaking micro-scratches on the polished surface of the work piece.

As a result, suitable methods of maximizing the efficiency, useful life,and other performance characteristics of diamond tools are continuallybeing sought.

SUMMARY OF THE INVENTION

It has been recognized by the inventor that it would be advantageous todevelop a method for making diamond tools which meets the challengesdiscussed above.

In one aspect, the present invention resolves the problems set forthabove by providing a method for forming metal bonded diamond or othersuperabrasive tools having a customized pattern of individual gritplacement. Because the distribution of the diamond grits is controlled,the diamond grits can be disposed in detailed patterns which cause aspecific pattern of tool wear, including uniform wear. Further, eachsuperabrasive grit is more fully utilized, and there is no need forredundant superabrasive grits as a back up. Therefore, the cost ofmaking the metal bond diamond or other superabrasive tools can beminimized by reducing the overall amount of superabrasive particlesneeded.

In accordance with another aspect of the present invention, the processinvolves providing a substrate, and then brazing a plurality ofsuperabrasive particles directly to an exposed surface of the substratein accordance with a predetermined pattern, thus chemically bonding thediamond particles in place on the substrate with a brazing alloy.

In one aspect of the invention, the brazing alloy may be provided as alayer of amorphous braze alloy, a powder, or rolled continuous film. Thebrazing alloy is chosen to contain an element which will chemically bondwith the superabrasive particles and the support material, such astitanium, vanadium, chromium, zirconium, molybdenum, tungsten,manganese, iron, silicon, aluminum and mixtures or alloys of theseelements. In a more detailed aspect of the present invention, thebrazing alloy may be applied either before or after the superabrasiveparticles are affixed to the substrate. A wide variety of brazing alloysmay be used in connection with the present invention to bond the diamondparticles to the substrate. The brazing alloy should braze thesuperabrasive particles to the substrate at a temperature which avoidsback-conversion of diamond to carbon. In a more detailed aspect of thepresent invention, the brazing is carried out at a temperature of lessthan about 1,100° C.

The process of bonding the diamond particles to the substrate using thebrazing alloy may be accomplished by a variety of methods. In oneaspect, the brazing alloy may be applied to the exposed surface of thesubstrate, after the diamond particles have been distributed thereon.The brazing alloy is then heated to a temperature sufficient to braze(i.e. chemically bond) the diamond particles to the substrate. This sameprinciple applies when the diamond particles are used in connection witha matrix support material rather than, or in addition to a substrate. Inanother aspect, the brazing alloy may be first placed on the exposedsurface of the substrate or matrix support material, and the diamondparticles are then distributed on or in the brazing alloy in accordancewith a predetermined pattern. Heating to a temperature sufficient toattain chemical bonding of the diamond particles to the substrate ormatrix support material then ensues.

The arrangement of the diamond particles in a predetermined pattern onthe matrix support material may be accomplished by a variety of methods.However, in one aspect, such a process includes using a template havinga plurality of apertures in a desired pattern. Typically, the templateis placed on the surface where the diamond particles are to be affixed,and the apertures are filled with diamond particles. As the particlesfill the apertures, they may be subjected to pressure or otherwise heldin place on the desired surface using an organic binder or adhesive.Next, the template may be removed, and depending on the requirements ofthe tool being formed, the diamond particles may be further adjusted onthe surface of the substrate. Because of the template, the particles areeach positively planted or positioned, at specific locations and heldaccording to a predetermined pattern on the substrate or matrix supportmaterial. In a more detailed aspect, a plurality of substrate or matrixsupport material layers with diamond particles thereon or therein, maythen be bonded together to form a tool having a three dimensionalarrangement of diamond or other superabrasive particles in accordancewith a predetermined pattern.

In another aspect of the present invention, the superabrasive particlesmay also be affixed to a transfer plate and then transferred to thesubstrate. In one aspect of this embodiment, the transfer plate can bemade of metal or plastic, and may be flexible or rigid. The affixing ofsuperabrasive particles to the transfer plate can be facilitated bycoating the transfer plate with a thin layer of adhesive. The templateis then used to distribute the superabrasive particles onto the transferplate in the desired predetermined pattern. The transfer plate havingsuperabrasive particles adhered thereto on one side is pressed againstthe substrate or matrix material. The superabrasive particles aretransferred to the matrix support layer by adhering to an adhesivecoated on the surface of the matrix support material. For ease ofprocessing, the adhesive coated on the substrate preferably adheres thesuperabrasive particles more strongly than the adhesive coated on thetransfer plate.

Next, the brazing alloy sheet is placed on top of the substrate havingabrasive particles adhered thereto. Alternatively, a brazing powder maybe sprinkled on the surface of the substrate having superabrasivesaffixed thereto. In an alternative aspect of the present invention, aslurry of brazing powder may be formed and then applied to the substrateor matrix support material having superabrasives adhered thereto, forexample, by spraying, pasting, etc.

In one variation of the transfer plate method, the transfer plate is asheet of amorphous braze which then becomes part of the final tool. Aplurality of superabrasives may be affixed to the sheet of amorphousbraze using an adhesive, or otherwise held in place, in a predeterminedpattern. The sheet of amorphous braze having superabrasives affixedthereon is then placed on a substrate. In a more detailed aspect of thisembodiment of the present invention, a template is used to create aspecific pattern of superabrasives on the sheet of amorphous braze in asimilar manner as when affixing the superabrasives to a substrate. Theapertures of the template are configured to admit one superabrasiveparticle in each aperture. Once all the apertures have been filled withsuperabrasive particles, any excess particles are removed, and theabrasive particles are pressed into the sheet of amorphous braze toembed them therein, by using a generally flat surface such as a steelplate. Alternatively, rather than pressing the particles into thebrazing alloy sheet, they may be held in place by a tacky substance, oradhesive, such as a glue, or other polymeric resin. The template is thenremoved and sheet of brazing alloy containing the abrasive particles isplaced on or affixed to a substrate with an adhesive, for exampleacrylic glue. Finally, the whole assembly is brazed in a vacuum furnaceto complete the brazing process and firmly fix the abrasive particles tothe substrate or matrix support material. In one aspect of theinvention, the flexible sheet of brazing alloy may also be affixed tothe substrate or matrix support material prior to introduction of theabrasive particles.

The arrangement of apertures used in the template may be configured in awide variety of patterns, including those determined to maximize toolperformance during specific applications. In one aspect, the pattern ofapertures, and thus the resulting predetermined pattern of diamondparticles, may be a uniform grid. In another aspect the superabrasiveparticles may be disposed in varied concentration patterns to compensatefor uneven wear. Thus, the diamond distribution for the cutting edge ofa saw may have a greater distribution of diamond particles on the leadedge and sides than on the middle portion which is generally subjectedto less wear. Likewise, the sizes of the superabrasive particles can becontrolled to provide a cutting, grinding, etc., surface which istailored to the particular uses and wear patterns for the tool.

In another aspect of the present invention a matrix support material maybe used that consists solely, or essentially, of a sheet of amorphousbrazing alloy. As such, the superabrasive particles can be distributedor planted in the sheet of brazing alloy. The superabrasive embeddedsheet of brazing alloy can then be bonded directly to a tool substrateor matrix support material. Alternatively, the superabrasive particlesmay be glued to a tool substrate or matrix support material using asuitable binder. Then the sheet of brazing alloy may then be applied tothe substrate or matrix support material, and the assembly is heatedabove the melting point of the braze. Thus the molten braze canchemically bond with the superabrasive particles and the substrate ormatrix support material. In another alternative embodiment the sheet ofbrazing alloy having superabrasive particles is layered with a thinlayer of unmelted metal.

In accordance with still yet another aspect of the present invention,the matrix support material may contain ingredients designed to enhancecertain properties. For example, hard materials such as tungsten,tungsten carbide and silicon carbide may be added to increase wearresistance. Soft materials, such as molybdenum sulfide, copper, andsilver, may also be added as solid lubricants.

In a yet more detailed aspect of the present invention, after heatingthe assembly of brazing alloy and abrasive particles, a layer of overlaymaterial may be affixed to the working surface of the brazing alloy tocreate a smooth working surface. Because of the molten state and surfacetension that the brazing alloy sheet endures during the heating process,the finally formed working surface thereof may be quite rough,containing many jagged points that are easily flaked off during use.This is of particular concern during fine polishing and dressingapplications where the workpiece may be damaged as a result of looseparticulates. The overlay material has a predetermined thickness, so asnot to interfere with the polishing or dressing capabilities of theabrasive particles. In addition, the overlay material generallycomprises any one of many metallic substances, such as nickel, tungsten,cobalt, chromium, or a zirconium nickel alloy. The overlay material maybe applied by several methods, but in certain aspects, may be applied byeither electroplating or physical vapor deposition (PVD) processes.

In another aspect of the present invention, a thin coating of optionalanti-corrosive material may also be applied to the diamond toolfollowing the brazing process. Addition of the anti-corrosive materialeffectively “seals” the working surface of the tool. Thereby protectingthe abrasive particles, the brazing alloy, and/or the overlay materialfrom chemical attack by various chemicals and/or coolants found inactual use of the tool. The anti-corrosive material generally includes asuper-abrasive material, such as diamond-like carbon, or amorphousdiamond. Similar to the overlay material, the anti-corrosive layer mayhave a predetermined thickness, so as effectively seal the workingsurface of the tool without interfering with the performance of theabrasive particles.

Yet another important aspect of the present invention is the ability tospecifically control the placement of various superabrasive particles onthe surface of the tool. Thus, for example, several sheet segments maybe assembled to form a tool precursor (see FIGS. 6A through 9 and 12C)for heat and pressure processing. Each segment is assembled by providinga thin layer of unmelted metal and disposing superabrasive grits on thelayer in a predetermined pattern. After the diamond particles are placedonto the thin layer of metal according to a predetermined pattern, asheet of amorphous brazing alloy is placed on the superabrasiveparticles to form a superabrasive layer sheet segment. The process maybe repeated until a desired number of layers have been formed. Theselayers are then assembled to form the desired three-dimensional body.Subsequently the diamond tool is consolidated (e.g., by sintering orinfiltration) to form the final product. By assembling substantiallytwo-dimensional segments to form a three-dimensional body, thedistribution of diamond grit in a tool can be positively controlled.Thus, diamond concentration in different parts of the same tool may beadjusted (see FIGS. 6A through 9). Such a control of diamonddistribution is highly desirable to improve the wear characteristics ofthe tool. For example, the sides of a diamond saw blade are often wornfaster then the center, so it is advantageous to add more diamond griton the sides (see FIG. 6B). The layers can be of uniform distributionpattern and concentration, or of differing distribution patterns,concentrations and/or particle size.

By assembling layers of metal matrix having superabrasives thereon in apredetermined pattern and concentration into a three dimensional body,the present invention not only provides the desirable diamonddistribution pattern in the tool body, but also provides the flexibilityfor possible manipulation of diamond concentration at different parts ofthe same tool body. Thus, for example, diamond particles can be disposedin denser concentrations in some layers than others, and the layers withthe greater diamond concentrations can be disposed within thethree-dimensional structure created in such a manner as to prevent theuneven wear patterns that are typical in many prior art abrasive tools.

Another example of the importance of improving the performance ofabrasive tools by employing a specific pattern or design of abrasiveparticles is in dressing applications. As indicated above, the use of atemplate allows the positioning or placement of abrasive particles, eachat specific locations in accordance with a predetermined pattern. In oneaspect, such patterns may be designed to present specific gaps orconfigurations that enhance the grooming of a CMP pad. For example, theworking surface of the CMP pad dresser may be configured to facilitatethe rising of the CMP pad under an interior, or central portion of thedresser, rather than only along an outside or “leading edge” thereof.Such additional rising allows the dresser to more effectively cut intoand groom the pad.

Use of the template also provides the ability to uniformly space theabrasive particles on the substrate. Uniform spacing and uniform size ofeach abrasive particle is ensured through the use of a template asdescribed above. Further, the use of a brazing alloy in a sheet or cutout with an even surface, in connection with uniformly sized abrasiveparticles that are adhered thereto, allows the creation of a uniformheight between the abrasive particles.

There has thus been outlined, rather broadly, various features of theinvention so that the detailed description thereof that follows may bebetter understood, and so that the present contribution to the art maybe better appreciated. Other features of the present invention willbecome clearer from the following detailed description of the invention,taken with the accompanying claims, or may be learned by the practice ofthe invention.

Additional features and advantages of the invention will be apparentfrom the detailed description which follows, taken in conjunction withthe accompanying drawings, which together illustrate, by way of example,features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a final tool segment produced in accordancewith an embodiment of the present invention;

FIG. 2 is a side view of a segment showing placement of superabrasiveparticles using a template;

FIG. 3 is a side view of a segment showing a method of placingsuperabrasive particles on a substrate using a transfer plate;

FIG. 4 is a side view of a segment showing an alternative method offorming a pattern of superabrasive particles;

FIG. 5 is a side view of a precursor segment showing a possibleplacement of the braze alloy;

FIG. 6A shows a segment from a super abrasive tool formed by a pluralityof linear, longitudinal layers disposed adjacent one another to form athree-dimensional super abrasive member;

FIG. 6B shows a cross-sectional view of one typical configuration of thetool segment shown in FIG. 6A, wherein a layer formed by a matrixsupport material and a relatively large superabrasive is sandwichedbetween two layers of matrix support materials, which have smaller grit,and higher concentration of the abrasive;

FIG. 7A shows a segment from a superabrasive tool formed by a pluralityof arcuate, longitudinal layers, which are attached to one another toform a three-dimensional super abrasive member;

FIG. 7B shows a cross-sectional view of a plurality of layers matrixsupport material as may be used with the segment shown in FIG. 7A;

FIG. 8 shows another possible layout of a segment of a cutting tool withtransverse layers configured with a denser concentration of abrasivematerial disposed at a forward, cutting end of the three-dimensionalsuper abrasive member;

FIG. 9 shows yet another layout of a segment wherein a three-dimensionalsuper abrasive member is formed with progressively denser abrasivedistribution toward the upper surface of a tool with horizontal layers;

FIGS. 10A through 10D show one possible method for forming layers withcontrolled superabrasive distribution within the layer;

FIGS. 11A through 11C show an alternate method for forming one or morelayers with controlled superabrasive distribution;

FIGS. 12A through 12C show another alternative method for forming one ormore layers with controlled superabrasive distribution using a sheet ofamorphous brazing alloy.

FIG. 13 shows a side view of a consolidated tool segment formed frommultiple layers having a three-dimensional pattern of superabrasives.

DETAILED DESCRIPTION

Reference will now be made to the exemplary embodiments illustrated inthe drawings, and specific language will be used herein to describe thesame. It will nevertheless be understood that no limitation of the scopeof the invention is thereby intended. Alterations and furthermodifications of the inventive features, process steps, and materialsillustrated herein, and additional applications of the principles of theinventions as illustrated herein, which would occur to one skilled inthe relevant art and having possession of this disclosure, are to beconsidered within the scope of the invention. It should also beunderstood that terminology employed herein is used for the purpose ofdescribing particular embodiments only and is not intended to belimiting.

A. Definitions

In describing and claiming the present invention, the followingterminology will be used.

The singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, reference to“a matrix material” includes reference to one or more of such materials,and reference to “an alloy” includes reference to one or more of suchalloys.

As used herein, “substantially free of” refers to the lack of anidentified element or agent in a composition. Particularly, elementsthat are identified as being “substantially free of” are eithercompletely absent from the composition, or are included only in amountswhich are small enough so as to have no measurable effect on thecomposition.

As used herein, “predetermined pattern” refers to a non-random patternthat is identified prior to construction of a tool, and whichindividually places or locates each superabrasive particle in a definedrelationship with the other diamond particles, and with theconfiguration of the tool. For example, “positively planting particlesin a predetermined pattern” would refer to positioning individualparticles at specific non-random and pre-selected positions. Further,such patterns are not limited to uniform grid patterns but may includeany number of configurations based on the intended application.

As used herein, “amorphous braze” refers to a homogenous brazecomposition having a non-crystalline structure. Such alloys containsubstantially no eutectic phases that melt incongruently when heated.Although precise alloy composition is difficult to ensure, the amorphousbrazing alloy as used herein should exhibit a substantially congruentmelting behavior over a narrow temperature range.

As used herein, “uniform grid pattern” refers to a pattern of diamondparticles that are evenly spaced from one another in all directions.

As used herein, “irregularly shaped” refers to a shape that is not astandard geometric shape, e.g. shapes that are not round, oval, square,etc.

As used herein, “matrix,” “matrix support material,” “matrix supportlayer,” and “matrix material,” may be used interchangeably, and refer toa non-sintered particulate material to which superabrasive particles maybe bonded. Notably, sintering or consolidation of the particulatematerial may occur during a process of chemically bonding superabrasiveparticles thereto. In one aspect, the superabrasive particles may bebonded or fixed to a surface of the matrix. In another aspect, thesuperabrasive particles may be fixed or planted into the matrix. In yetanother aspect, the matrix material may take the shape of a tool body.In a further aspect, the matrix material may take the shape of a sheethaving a specified thickness.

As used herein, “substrate” refers to a solid metal material. While manysolid metal materials may be a product of metal particulate sintering orconsolidation, it is to be understood, that as used herein, “substrate”does not include powdered or particulate metal materials that have notyet been sintered or consolidated into a solid mass or form.

As used herein, “alloy” refers to a solid or liquid mixture of a metalwith a second material, said second material may be a non-metal, such ascarbon, a metal, or an alloy which enhances or improves the propertiesof the metal.

As used herein, “metal brazing alloy,” “brazing alloy,” “braze alloy,”“braze material,” and “braze,” may be used interchangeably, and refer toa metal alloy which is capable of chemically bonding to superabrasiveparticles, and to a matrix support material, or substrate, so as tosubstantially bind the two together. The particular braze alloycomponents and compositions disclosed herein are not limited to theparticular embodiment disclosed in conjunction therewith, but may beused in any of the embodiments of the present invention disclosedherein.

As used herein, the process of “brazing” is intended to refer to thecreation of chemical bonds between the carbon atoms of the superabrasiveparticles and the braze material. Further, “chemical bond” means acovalent bond, such as a carbide or boride bond, rather than mechanicalor weaker inter-atom attractive forces. Thus, when “brazing” is used inconnection with superabrasive particles a true chemical bond is beingformed. However, when “brazing” is used in connection with metal tometal bonding the term is used in the more traditional sense of ametallurgical bond. Therefore, brazing of a superabrasive segment to atool body does not require the presence of a carbide former.

As used herein, “superabrasive particles” and “superabrasive grits” maybe used interchangeably, and refer to particles of either natural orsynthetic diamond, super hard crystalline, or polycrystalline substance,or mixture of substances and include but are not limited to diamond,polycrystalline diamond (PCD), cubic boron nitride (CBN), andpolycrystalline cubic boron nitride (PCBN). Further, the terms “abrasiveparticle,” “grit,” “diamond,” “PCD,” “CBN,” and “PCBN,” may be usedinterchangeably.

As used herein, in conjunction with the brazing process, “directly” isintended to identify the formation of a chemical bond between thesuperabrasive particles and the identified material using a singlebrazing metal or alloy as the bonding medium.

As used herein, “precursor” refers to an assembly of superabrasiveparticles, substrate or matrix support material, and/or a braze alloy. Aprecursor describes such an assembly prior to the brazing and/orsintering process, i.e. such as a “green body”.

As used herein, “aperture” refers to an opening through a templatesurface which has a predetermined size and shape depending on theintended application. For example, the aperture size may be designed toaccommodate a plurality of superabrasive particles of a given mesh size.However, it is often desirable to design the apertures such that onlyone superabrasive particle is accommodated by each aperture.

As used herein, “euhedral” means idiomorphic, or having an unalterednatural shape containing natural crystallographic faces.

As used herein, “sharp portion” means any narrow apex to which a crystalmay come, including but not limited to corners, ridges, edges, obelisks,and other protrusions.

As used herein, “metallic” means any type of metal, metal alloy, ormixture thereof, and specifically includes but is not limited to steel,iron, and stainless steel.

As used herein with respect to distances and sizes, “uniform” refers todimensions that differ by less than about 75 total micrometers.

Concentrations, amounts, and other numerical data may be presentedherein in a range format. It is to be understood that such range formatis used merely for convenience and brevity and should be interpretedflexibly to include not only the numerical values explicitly recited asthe limits of the range, but also to include all the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited.

For example, a concentration range of about 1% w/w to about 4.5% w/wshould be interpreted to include not only the explicitly recitedconcentration limits of 1% w/w to about 4.5% w/w, but also to includeindividual concentrations such as 2% w/w, 3% w/w, 4% w/w, and sub-rangessuch as 1% w/w to 3% w/w, 2% w/w to 4% w/w, etc. The same principleapplies to ranges reciting only one numerical value, such as “less thanabout 4.5% w/w,” which should be interpreted to include all of theabove-recited values and ranges. Further, such an interpretation shouldapply regardless of the breadth of the range or the characteristic beingdescribed.

B. The Invention

Reference will now be made to the drawings in which the various elementsof the present invention will be given numeral designations and in whichthe invention will be discussed. It is to be understood that thefollowing description is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the appended claims.

Referring now to FIG. 1, a plurality of superabrasive particles 20 arebrazed to an exposed surface of substrate 102 in accordance with apredetermined pattern. A braze material 25 is used to braze or bond thesuperabrasive particles to the substrate. In keeping with the presentinvention, a variety of methods may be used to obtain the desiredresults and are discussed in more detail below.

The substrate may include a variety of materials, such as variousmetals. Examples of specific metals include without limitation, cobalt,nickel, iron, copper, carbon, and their alloys or mixtures (e.g.tungsten or its carbide, steel, stainless steel, bronze, etc). Thepresent invention is useful for a variety of diamond tools such as forgrinding, polishing, cutting, dressing or any tool used to removematerial from a workpiece. For example, saws are not limited to, but mayinclude, circular saws, straight blades, gang saws, reciprocating saws,frame saws, wire saws, thin-walled cutoff saws, dicing wheels, and chainsaws. In another aspect, the diamond tool may be a CMP pad conditioner.

Typically, the substrate has an exposed surface upon which thesuperabrasive particles are to be affixed and may be substantially flator contoured and may have multiple faces, such as in some drill bits orcircular saws. However, in one embodiment of the present invention, thesuperabrasives may be bonded to a matrix support material rather thandirectly to a substrate. The matrix support material may either besufficiently configured to act as a tool body, or may be further coupledto a substrate to form a complete tool.

In another alternative embodiment, the abrasive particles may betemporarily affixed to a substrate with an acrylic glue, or otheradhesive using the template as described below in order to preventmovement during the brazing process. Most common adhesives will vaporizeat temperatures above about 400° C. and do not chemically react with thebraze alloy or superabrasive particles.

The brazing alloy of the present invention may be provided as a thinsheet, powder, or continuous sheet of amorphous braze alloy. There aremany ways that the brazing alloy can be provided in accordance with thepresent invention. For example, a brazing alloy powder can first bemixed with a suitable binder (typically organic) and a solvent that candissolve the binder. This mixture is then blended to form a slurry ordough with a proper viscosity. In order to prevent the powder fromagglomeration during the processing, a suitable wetting agent (e.g.,menhaden oil, phosphate ester) may also be added. The slurry may then besprayed or otherwise applied to the matrix support material and/orsuperabrasive particles. In another embodiment, the slurry can then bepoured onto a plastic tape and pulled underneath a blade or levelingdevice. By adjusting the gap between the blade and the tape, the slurrycan be cast into a plate with the desired thickness. The tape castingmethod is a well-known method for making thin sheets out of powderedmaterials and works well with the method of the present invention.

The brazing alloy may also be provided as a sheet of amorphous brazingalloy. The sheet of amorphous brazing alloy may be flexible or rigid andmay be shaped based on the desired tool contours. This sheet of brazingalloy also aids in the even distribution of the braze over the surfaceof the tool. The sheet of brazing alloy contains no powder or binder,but rather is simply a homogenous braze composition. Amorphous brazingalloys have been found to be advantageous for use in the presentinvention, as they contain substantially no eutectic phases that meltincongruently when heated. Although precise alloy composition isdifficult to ensure, the amorphous brazing alloy used in the presentinvention should exhibit a substantially congruent melting behavior overa relatively narrow temperature range. Thus, during the heating portionof the brazing process the alloy does not form grains or a crystallinephase in substantial quantities, i.e. via vitrefication. Further, themelting behavior of the amorphous braze alloy is distinct from sinteringwhich requires the reduction or elimination of voids between particlesof alloy material which does not exist in the amorphous form of thealloy. However, the originally amorphous braze may form non-homogeneousphases during crystallization via the slower cooling process. Generally,amorphous alloys are formed by quickly quenching the liquid into a solidto avoid localized crystallization and variations in composition.Notably, in each of the processes recited herein, the brazing alloy maybe presented as either a sheet, film, or other punched out layer thatcorresponds to the desired tool segment shape.

Alternatively, a powdered brazing alloy can be mixed with a suitablebinder and its solvent to form a deformable cake. The cake can then beextruded through a die with a slit opening. The gap in the openingdetermines the thickness of the extruded plate. Alternatively, thematerial can also be drawn between two rollers with adjustable gap toform sheets with the right thickness. In another aspect, the brazepowder may be showered directly onto diamond particles and substrate asmore fully elaborated below.

It is desirable to make the sheets pliable for subsequent treatments(e.g., bending over the tool substrate). Therefore, a suitable organicplasticizer can also be added to provide the desired characteristics.

The use of organic agents for powder (metal, plastics, or ceramics)processing is documented in many textbooks and it is well known by thoseskilled in the art. Typical binders include polyvinyl alcohol (PVA),polyvinyl butyral (PVB), polyethylene glycol (PEG), paraffin, phenolicresin, wax emulsions, and acrylic resins. Typical binder solventsinclude methanol, ethanol, acetone, trichlorethylene, toluene, etc.Typical plasticizers are polyethylene glycol, diethyl oxalate,triethylene glycol dihydroabietate, glycerin, octyl phthalate. Theorganic agents so introduced are to facilitate the fabrication of metallayers. They must be removed before the consolidation of metal powders.The binder removal process (e.g., by heating in a furnace withatmospheric control) is also well known to those skilled in the art.

In one aspect, the brazing alloy may be substantially free of zinc,lead, and tin. One commercially available powdered braze alloy, which issuitable for use with the present invention, is known by the trade nameNICROBRAZ LM (7 wt % chromium, 3.1 wt % boron, 4.5 wt % silicon, 3.0 wt% iron, a maximum of 0.06 wt % carbon, and balance nickel), made by WallColmonoy Company, Madison Heights, Mich. Other suitable alloys includedcopper, aluminum, and nickel alloys containing chromium, manganese,titanium, and silicon. In one aspect, the brazing alloy may includechromium. In another aspect, the brazing alloy may include a mixture ofcopper and manganese. In an additional aspect, the amount of chromium,manganese, and silicon may be at least about 5 percent by weight. Inanother aspect, the alloy may include a mixture of copper and silicon.In yet another aspect, the alloy may include a mixture of aluminum andsilicon. In a further aspect, the alloy may include a mixture of nickeland silicon. In another aspect, the alloy may include a mixture ofcopper and titanium.

Preferably, the diamond braze contains at least 3% by weight of acarbide forming member selected from the group consisting of chromium,manganese, silicon, titanium, and aluminum, and alloys and mixturesthereof. Additionally, the diamond braze should have a liquidustemperature of less than 1,100° C. to avoid damage to the diamond duringthe brazing process. One commercially available sheet of amorphousbrazing alloy which melts at a sufficiently low temperature is anamorphous brazing alloy foil (MBF) manufactured by Honeywell having theNICROBRAZ LM composition. These foil sheets are about 0.001″ thicknessand typically melt at between about 1,010° C. and about 1,013° C.

In one aspect, the brazing process may be carried out in a controlledatmosphere, such as under a vacuum, typically about 10⁻⁵ torr, an inertatmosphere (e.g., argon (Ar) or nitrogen (N₂)), or a reducing atmosphere(e.g., hydrogen (H₂)). Such atmospheres may increase the infiltration ofthe brazing alloy into the matrix support material, and therefore,enhance the diamond-braze and matrix-braze bonding.

Referring now to FIG. 2, a substrate 102 is selected and a template 110is laid on the top of the substrate. The template 110 contains apertures114 that are larger than one superabrasive particle, but smaller thantwo abrasive particles, thereby allowing a single particle of theabrasive to be disposed at each specific location. The thickness of thetemplate is preferably between ⅓ to ⅔ of the height of the averageabrasive particle. However, other thicknesses may be used if appropriateaccommodations are made for seating the abrasive particles in thedesired locations. In some aspects, the thickness of the template may beup to two (2) times the height of the abrasive particles. An adhesivemay be applied to the surface of the substrate to hold the superabrasiveparticles in place during the brazing process.

After the template 110 is properly positioned, a layer of abrasiveparticles 20 is then spread over the template so that each aperture 114receives an abrasive particle. Those particles not falling into theapertures in the template are removed by tilting the substrate, sweepingthe template with a broom, or some other similar method. Optionally, agenerally flat surface, such as a steel plate, may then be laid over thesuperabrasive particles, which rest in the apertures in the template.The flat surface presses the superabrasive particles to seat theparticles. The pressed particles are therefore firmly attached to thesubstrate by either slight mechanical impression into the substrate, orinto a braze layer (not shown), or adhesive layer (not shown) which wasapplied to the exposed surface of the substrate prior to placing thesuperabrasive particles thereon. The template 110 is then removed suchthat the superabrasive particles 20 remain in place on the substrate 102in accordance with the predetermined pattern of the template.

Alternatively, as shown in FIG. 3, the substrate may be a transfer plate106 onto which the superabrasive particles 20 are affixed to one sideusing a thin adhesive film (not shown). Optionally, the same methods asdescribed above with regard to using a template 110 to achieve aparticular pattern of superabrasive particles may be used to effectparticle placement. The transfer plate 106 having superabrasiveparticles 20 affixed thereon is then pressed against a substrate 102.The transfer plate may be made of metal or plastic, however it has beenfound that a transparent plastic transfer plate increases ease of useand facilitates monitoring of the process. Affixing of the particles tothe transfer plate may be accomplished using any adhering means, such asan adhesive. In order to facilitate transfer of the superabrasiveparticles to the substrate 102 an adhesive layer (not shown) whichadheres the particles 20 more strongly to the substrate 102 than to thetransfer plate can be used. The transfer plate is then removed andtreatment such as adding a braze to form a tool precursor and heating toproduce the final product may be performed. Therefore, the abrasiveparticles are transferred to the substrate in the pattern dictated bythe template.

In another alternative embodiment, the transfer sheet 106 may be a sheetof amorphous brazing alloy. In a similar process to that describedabove, the superabrasive particles 20 are affixed to a substrate. First,a template 110 having apertures 114 is placed upon a sheet of brazingalloy 106, as illustrated in FIG. 4. In one aspect of the presentinvention, the sheet may be a sheet or film of continuous amorphousbrazing alloy, as described above. The use of the template allowscontrolled placement of each abrasive particle at a specific location bydesigning the template with apertures in a desired pattern.

After the template 110 is place on the brazing alloy sheet, theapertures 114 are filled with abrasive particles 20. The apertures havea predetermined size, so that only one abrasive particle will fit ineach. Any size of abrasive particle, or grit is acceptable, however inone aspect of the invention, the particle sizes may be from about 100 toabout 350 micrometers in diameter. Although various aperture sizes andshapes would restrict access to one particle per aperture, the aperturesof the present invention may be designed for very careful placement ofthe superabrasive particles. Thus, for average particle sizes of 100micrometers the apertures could be designed about 150 micrometersacross.

In another aspect of the invention, the size of the apertures in thetemplate may be customized in order to obtain a pattern of abrasiveparticles having a size within a uniform size range. In one particularembodiment of CMP pad dressing, the apertures of the template aresufficient to select only grits within a size range having a variance nogreater than 50 micrometers. This uniformity of grit size contributes tothe uniformity of CMP pad dressing, as the workload of each abrasiveparticle is evenly distributed. In turn, the even workload distributionreduces the stress on individual abrasive particles, and extends theeffective life of the CMP pad dresser. In various superabrasive tools,the template may take a wide variety of configurations. The patterns mayinclude various arrangements, as well as, include multiple sizeapertures to accommodate differing size superabrasive particles in thesame tool in which case the larger particles would be applied firstfollowed by the smaller particles.

After the apertures of the template are all filled with superabrasiveparticles, any excess abrasive particles are removed, and optionally aflat surface is applied to the abrasive particles. The flat surfaceshould be of an extremely strong, rigid material, so that it is capableof pushing abrasive particles down into the brazing alloy sheet or film106. Such materials typically include, but are not limited to steel,iron, alloys thereof, etc.

After removing the template, the flat surface may be used again to pressthe abrasive particles firmly into the sheet of brazing alloy. While aflat surface is preferable, those skilled in the art will appreciatethat there may be occasions when it is desirable to have some of theabrasive particles extend outwardly from the final tool more than otherabrasive particles. In such situations, a contoured or otherwise shapedsurface could be used to seat some of the abrasive particles deeper intothe sheet of brazing alloy, than other particles. The abrasive particleswill thus extend away from the substrate to a predetermined height.

While the method described above to press the superabrasive particlesinto the brazing alloy is preferred for many applications, there areinstances where it is desirable to have the abrasive particles extendoutwardly from the sheet of brazing alloy. For example, some tools mayonly have one layer of abrasive. This can be accomplished simply byleaving the template 110 in place when pressing the superabrasives usinga flat surface, and not further pressing the particles into the brazingalloy once the template has been removed.

In the alternative, the sheet or film of brazing alloy in FIGS. 3through 5 is formed to be of a lesser thickness than the cross-sectionalthickness or diameter of the superabrasive particles 20. When theparticles are pressed into the sheet 106, the thickness of the sheetforces the particles to protrude from the sheet of brazing alloy. Thesheet is then applied to the matrix support material in a mannerdiscussed above.

In creating the predetermined pattern of the present invention, thespacing of the apertures in the template, while non-random, need not beuniform. Rather, variations in spacing can be provided to facilitatedifferent concentrations on various areas to facilitate differentconcentrations on various portions of the sheet of amorphous brazingalloy. Likewise, by controlling the size of the apertures and the orderin which the diamond particles are placed in the apertures, a singlelayer could be provided with particles of different sizes.

In a more detailed aspect of the present invention, superabrasiveparticle height may be important in CMP pad dresser performance. Auniform particle height can be determined by the thickness of thetemplate 110, and in a preferred embodiment, each abrasive particle willextend to within 50 micrometers of this distance. As such, each abrasiveparticle grooms to substantially the same depth on the CMP pad. However,it is to be understood that in certain applications, grit height may notbe desired to be uniform. As such, those of ordinary skill in the artwill recognize that grit patterns of varied height may be provided by soconfiguring the template, and the surface used to press the particles toprovide such a design.

Abrasive particles 20 as shown in FIGS. 1-12C are various shapes. Thescope of the present invention encompasses abrasive particles of anyshape, including euhedral, or naturally shaped particles. However, inone embodiment, the abrasive particles have a predetermined shape with asharp point extending in a direction away from the substrate.

In an alternative embodiment, rather than pressing the abrasiveparticles into the sheet of brazing alloy, they may be fixed in thetemplated position by disposing an adhesive on the surface of the sheetof brazing alloy. In this manner, the particles remain fixed in placewhen the template is removed, and during heat processing.

While the use of the sheet of amorphous brazing alloy 106 been discussedwith respect to the patterned distribution of superabrasive particles,it is equally applicable to the random distribution of diamond particleson a matrix support material. Thus, the superabrasive particles may bedistributed on either the sheet of brazing alloy or a matrix supportmaterial without the use of a template or otherwise creating apredetermined pattern. Similar methods and arrangements could beemployed as described above in connection with the use of a template.

After the superabrasive particles are at least partially embedded in, oradhered to, the sheet of brazing alloy 106, the sheet is affixed to thesubstrate 102 as shown in FIG. 5. Alternatively, in some embodiments,the sheet of brazing alloy may be first affixed to the substrate, andthe abrasive particles subsequently added thereto using the templateprocedure described herein. In another alternative embodiment, the sheetof brazing alloy having superabrasive particles affixed thereto isapplied to the exposed surface of the substrate in such a manner thatthe superabrasive particles are oriented between the sheet and thesubstrate as shown in FIG. 3.

The brazing alloy used in several embodiments of the present inventionmay be any brazing material known in the art, but in one aspect, may bea nickel alloy that has a chromium content of at least about 2% byweight. A brazing alloy of such a composition will be nearly super hardin and of itself, and less susceptible to chemical attack from solutionsused in various applications such as an abrasive containing slurry. Insuch an embodiment, additional anti-corrosive layers or overlay materialwould be optional.

Because the abrasive particles are firmly held in, or on the sheet ofbrazing alloy, the surface tension of the liquid brazing alloy isinsufficient to cause particle clustering during the brazing process.Additionally, braze thickening occurs to a much lesser degree and few orno “mounds” are formed. Rather, the braze 25 forms a slightly concavesurface between each abrasive particle, due to the wetting action of thechemical bonding between the braze and the particles, which providesadditional structural support, as shown in FIG. 1. In one embodiment,the thickness of the sheet of amorphous brazing alloy 106 ispredetermined to allow at least about 10% to about 90% of each abrasiveparticle to protrude above the outer, or working, surface of brazingmaterial. In another aspect, when an overlay material is used, theabrasive particles may be selected or placed, so that at least about 10%to about 90% of each abrasive particle protrudes above the outer, orworking, surface of the overlay material.

In addition to the specific methods of embedding, or adhering theabrasive particles to the sheet of brazing alloy, those skilled in theart will recognize suitable alternative procedures, such as fixing theabrasive particles to the substrate, and then placing the braze thereon.In this case, the particles may be positioned on the substrate using thetemplate method recited above, and held in place by glue, or othersuitable binder. Alternatively, a powdered braze material is thenshowered, or placed on the substrate around the abrasive particles andheated to cause the braze material to form chemical bonds with thesuperabrasive particles and bond to the substrate.

Once the superabrasive particles and brazing alloy have been placed onthe substrate, or matrix support material, to form a superabrasive toolprecursor the precursor is heated to braze the superabrasives to thematrix support material. The selection of the brazing alloy is importantand directly affects the final tool properties such as durability andstrength. Although many types of brazing alloys are commerciallyavailable, the brazing alloys useful in connection with the presentinvention are limited. The brazing alloy should contain a carbide formeras discussed above, such as titanium, vanadium, chromium, zirconium,molybdenum, tungsten, manganese, iron, silicon, aluminum, and mixturesor alloy thereof.

Of particular importance are chromium, manganese, silicon or alloys ormixtures thereof and have proven effective in the present invention. Thecarbide former may be present in the brazing alloy between about 2% andabout 50% by weight of the brazing alloy. Examples of these brazes areNICROBRAZ LM (Ni—Cr—B—Si—Fe), manufactured by Wall Colmonoy Company(U.S.A.), with a melting range of 970-1000° C., and 21/80 (Cu—Mn—Ni),manufactured by Degussa (Germany), with a melting range of 970-990° C.Other possible brazes include: Cu—Mn alloy near the eutectic composition(about 25 wt % Mn) with a melting point of about 880° C.; Ni—Si alloynear the eutectic composition (about 50 wt % Si) with a melting point ofabout 970° C.; Cu—Si alloy near the eutectic composition (about 30 wt %Si) with a melting point of about 810° C.; Al—Si alloy near the eutecticcomposition (about 15 wt % Si) with a melting point of about 600° C.

The above-recited examples of diamond brazes cover a wide range ofmechanical properties and infiltration or sintering temperatures(generally about 50° C. above the liquidus temperature). Various alloysof these brazes may also be used for further adjustments of brazingtemperature and mechanical properties. The selection of diamond brazedepends largely on the intended application. In general, more severeapplications, such as sawing granite, concrete, or asphalt, wouldrequire a stronger diamond grit that may tolerate a higher temperatureof brazing. Brazes which melt at higher temperatures are, in general,more wear resistant. On the other hand, less demanding applications,such as sawing limestone or marble, require lower strength diamond grit.Such a diamond is degraded easily at high temperature so it must bebrazed at a lower temperature. Brazes of this type are typically lesswear resistant.

Brazing material should be kept to a minimum in order to avoidcompletely covering the abrasive particles. This problem is compoundedby the fact that typical brazing materials are mechanically very weak.This mechanical weakness offsets the strength of the chemical bondscreated between the abrasive particles and the brazing material. Infact, when dislodgment occurs, the chemical bonds between the abrasiveparticles and the brazing material are strong enough that the brazingmaterial itself will often shear off along with detached abrasiveparticles. The brazing material is also very susceptible to chemicalattack by the abrasive slurry. This contributes to the detachment ofabrasive particles, as it further weakens the brazing material, which isalready mechanically weak.

While prior art brazes typically include metals which were designed tofacilitate flow of the braze material, such as zinc, lead and tin, ithas been found in accordance with the present invention that suchmaterials actually impair the brazing process. The prior art materialsare generally more volatile, and have a tendency to contaminate thevacuum or inert atmosphere used in infiltration. While very smallamounts of the volatile metals will not significantly interfere withbrazing, amounts over about 1 or 2 percent by weight can inhibit properinfiltration. As used herein, substantially free of volatile metals, orsubstantially free of zinc, etc. is used to characterize such asituation in which the volatile metal is present in sufficiently smallamounts as to not provide any meaningful impediment to infiltration andbrazing.

It is important that the brazing temperature be kept lower than themelting point of the substrate so the tool body can maintain the shapeduring the brazing of the superabrasive particles. Moreover, the brazingtemperature must also be low enough to not cause diamond to degrade,typically less than about 1,100° C. For embodiments involvinginfiltration, a temperature typically 50° C. above the liquidustemperature of the braze alloy is required. In addition to control thebrazing temperature, the brazing time should also be kept short so thebraze will not react excessively with diamond or the substrate. In theformer case, diamond may also be degraded. In the later case, thealloying with the surface of the substrate may raise the melting pointof the diamond braze. As a result, the diamond braze may solidifygradually and eventually stop flowing. Also, a coarse braze powder willrequire longer heating times and/or temperatures.

An additional consideration in selection of a brazing alloy is that itshould also wet the superabrasive particles and chemically bond with thesuperabrasives. Therefore, as the brazing alloy 25 bonds with thesuperabrasive particles the alloy creeps up the sides of thesuperabrasives as can be seen in FIG. 1. This wetting action isbeneficial for several reasons including improved mechanical support forthe particles, as well as the strong carbide bonds. Typically, a carbideformer contained in a suitable solvent alloy meets this requirement.However, various carbide formers may be adversely impacted by thebrazing atmosphere.

The atmospheric environment for brazing also may be controlled toprovide superior performance. For example, if the braze materialcontains a strong attractor of oxygen or nitrogen, such as titanium, ahigh degree of vacuum (10⁻⁶ torr maximum), or a dew point below −60° C.,must be maintained during the brazing process. This restraint often addsunnecessary costs to manufacturing of diamond bond tools. The presenceof minute amounts of oxygen may oxidize the carbide former and preventthe formation of carbide bonds with the diamond. On the other hand, ifthe braze material contains a less sensitive getter, such as chromiumand manganese, a lower degree of vacuum (10⁻⁵ torr minimum) or ahydrogen atmosphere may be adequate for brazing. However, if the carbideformer reactivity is too low, such as with cobalt or nickel, minimalcarbide bonds will be formed with the diamond particles. Hence there isa compromise in selection of carbide formers between the ability to bondwith diamond and the tendency to oxidize.

After brazing, the produced part (e.g., a saw segment) may be trimmed(e.g., by grinding) to the finished dimension. It can then be mounted(e.g., by conventional brazing) onto a tool body (e.g., a round steelblade) to make a finished product.

As discussed above, this invention uses a diamond braze that wets thematrix support material of a diamond tool. Most diamond brazes can weteasily common matrix support materials with major constituents ofcobalt, nickel, iron, copper or bronze, so the brazing may proceedsmoothly. Referring again to FIG. 1, typically, the final diamond toolproduced in accordance with the method of the present invention includesdiamond particles 20 having carbide bonds with a component of the brazealloy, such as chromium, and a braze 25 containing various eutecticphases which includes both mechanical brazing and partial alloying withthe substrate 102.

In addition to brazing using the methods described above, the bonding ofthe diamond particles to the matrix material using the brazing alloy maybe accomplished by mixing a powdered form of brazing alloy with apowdered form of matrix material. The organic binder is then added, andthe matrix support material and brazing alloy are formed into a sheet,or layer as described above. Diamond particles are then distributed bybeing positioned or located in a predetermined pattern using a templateas described. The sheet may then be stamped, or pressed into desiredtool shapes, which are heated to a temperature sufficient to bond thediamond particles to the matrix support material using the brazingalloy, as well as to sinter together the metal particles of the matrix.Such a process generally may be accomplished using low temperatureswhich do not incur many of the afore-warned risks to the tool.

The most widely used matrix powder for making diamond tools (e.g., sawsegments) is cobalt powder. The standard sizes of cobalt powder formaking conventional diamond tools are less than 2 micrometers. In thelast decade, the diamond tool manufacturers have demanded finer andfiner matrix powders. The commercial suppliers (e.g., Eurotungsten Co.)are therefore, moving toward making ultrafine (one micrometer), and evenultra-ultrafine (submicron) powders. With such a trend, the sinteringtemperature is continuously decreasing. A lower sintering temperaturenot only reduces the degradation of diamond; it also reduces the cost ofmanufacturing. For example, the powder consumption is lower. Moreover,the oxidation loss of graphite mold is also minimized.

However, one embodiment of the present invention uses a diamond braze tofill up the pores of the matrix powder. Hence, coarse-sized powders,i.e. greater than 400 U.S. mesh or 34 microns, are preferred. Moreover,while conventional methods require the density be as high as possible sosintering can proceed rapidly, it is preferred in the present inventionto use a precursor with a lower packing density to allow the easy flowof the diamond braze. In fact, sometimes, the porosity of the precursorbody may be intentionally increased by using irregularly shaped matrixparticles. This preference, again, is contrary to the conventionalwisdom that requires the particles be as spherical as possible so thepacking density can be increased.

The use of a coarse matrix powder has other benefits. For example, acoarse powder can mix better with different compositions. Hence, thediamond grit may distribute more uniformly in the matrix. Moreover, acoarse powder has a smaller surface area, and hence, a lower frictionalforce for infiltration. Therefore, it can flow easier in the mold. Ofcourse, a coarse matrix powder is also much less expensive, so theproduction cost may be reduced.

It is important to note that this invention utilizes the matrix merelyas the network for holding the diamond grit in place. Hence, the matrixmay not have to be made of powder. For example, the matrix body may bemade of a piece of steel with openings that contain diamond grits of PCDbodies. Further, the superabrasive containing segments may be easilyformed to accommodate a variety of substrate shapes prior to brazing.

In another alternative embodiment of the present invention, athree-dimensional tool is formed having a predetermined pattern ofdiamond grits therein. By assembling substantially two-dimensionalsegments to form a three-dimensional body, the distribution of diamondgrit in a tool can be positively controlled. Thus, diamond concentrationin different parts of the same tool may be adjusted (see FIGS. 6Athrough 9). Such a control of diamond distribution is highly desirableto improve the wear characteristics of the tool. For example, the sidesof a diamond saw blade are often worn faster then the center, so it isadvantageous to add more diamond grit on the sides (see FIG. 6B).

Referring to FIG. 6A, there is shown a perspective view of a toolsegment, generally indicated at 10, formed by a plurality of layers, 14,16 and 18. Each of the layers 14, 16 and 18 is formed by matrix supportmaterial impregnated with diamond particles, indicated by the darkcircles 20, and has been infiltrated with a braze selected to chemicallybond to the diamond particles and the matrix support material, suchbonding firmly holds the particles in the matrix support material.Preferably, the diamond particles 20 constitute less than 50 percent ofthe matrix support material-diamond mixture, and more preferably lessthan 40 percent. Keeping the amount of diamond particles to the minimumhelps to minimize cost while optimizing the useful life of the product.Although FIGS. 6A through 9 show discrete layers of matrix supportmaterial, the final sintered tool segment is essentially a continuousmetal matrix having superabrasive particles distributed in a particularthree-dimensional pattern. Thus, the layers meld to form an essentiallyseamless unitary matrix having superabrasive particles therein. Thiscontinuous melded matrix improves the strength and durability of thefinal multi-layered tool.

As discussed in U.S. Pat. No. 6,159,286, which is incorporated herein,forming the segment 10 in a plurality of thin layers provides remarkablyimproved control over the distribution of the diamond particles 20. Bycontrolling the distribution of the diamond particles 20 within eachlayer and then combining layers, a three-dimensional segment can beformed in which distribution of the diamond particles is controlled ineach dimension. This, in turn, enables the formation of segments, whichare particularly adapted to the likely use of the segment, be it forpolishing, cutting, grinding, etc. By tailoring the distribution andconcentration of the super abrasive particles within the segment 10,more precise control is given over performance of the tool under actualworking conditions.

For example, when using a diamond saw blade to cut rocks (e.g.,granite), the two sides of the diamond saw segments are cutting morematerials than the center. As a result of uneven wear, the cross sectionof the saw segment becomes convex in shape with the center bulging aboveboth sides. This configuration typically slows the cutting rate of thesaw blade. Moreover, the protruding profile may also cause the saw bladeto deflect sideways in the cut slot. In order to maintain a straightcutting path, it is sometimes desirable to make a “sandwich diamondsegment” to reinforce both sides of the segment with layers impregnatedwith more diamond or superabrasive grits. Such a “sandwich segment” isdifficult to manufacture by mixing diamond grit with metal powder byconventional means, but it can be easily accomplished by methods of thepresent invention: first planting diamond grits with desirable patternsand concentrations in a metal matrix layer and then assembling thesemetal matrix layers with diamond grits impregnated in the predeterminedpatterns and concentrations together to form a sandwiched segment.

The present invention further improves the above technique byinfiltrating the matrix support material with a braze which is selectedto chemically bond to the diamond particles and to the matrix supportmaterial. Thus, while the placement of the diamond particles shown inFIG. 6A is a marked improvement over the prior art, an additionalincrease in the useful life of segment 10 is obtained by utilizing abraze to form a chemical bond, rather than merely relying on mechanicalretention of the diamond particles.

Likewise, the selective placement of differing sizes of diamondparticles can used to form a cutting segment formed to resist prematurewear to the sides of the segment, thereby extending the cuttingsegment's useful life. Referring specifically to FIG. 6B, there is showna cross-sectional view of the cutting segment 10 of FIG. 6A. Unlike thecutting segments of the prior art, the cutting segment 10 is formed ofthree layers, 14, 16 and 18 respectively. The middle layer 16 has aplurality of super abrasive particles 20 a, which are of a first size(e.g. 40/50 mesh) and a first concentration. The outer layers 14 and 18,in contrast, have a plurality of super abrasive particles 20 b, whichare of a second size (e.g. 50/60 mesh) smaller than the first size, andin a second concentration greater than that present in the middle layer16. The smaller, more densely distributed super abrasive particles 20 bprovide the outer layers 14 and 18 with a greater resistance to wear asthey cut through concrete, rock, asphalt, etc. Because the outer layers14 and 18 are more resistant to wear, the cutting segment 10 resistsformation of a convex outer surface, as has traditionally occurred withcutting elements. By maintaining a more planar cutting surface, thecutting segment is able to maintain a straight cutting path so it cancut more efficiently with a longer useful life. Moreover, by using asmaller grit on the flank of the saw, the finish of the cut surface issmoother and chipping of the workpiece can be avoided.

Furthermore, an additional increase in useful life is obtained byinfiltrating the matrix support material with a braze formed fromchromium, manganese, silicon, titanium, and/or aluminum, or an alloy ormixture thereof. While a wide variety of quantities of these materialsmay be used, it has been found that it is preferable if the chromium,manganese, silicon, titanium, or aluminum or alloy or mixture in thediamond braze constitutes at least 3 percent of the braze by weight (andmore preferably 5 percent). The braze fills the pores in the matrixsupport material, which is typically powder selected from the groupincluding iron, cobalt, nickel or alloys or mixtures thereof.

Another advantage to the use of multiple layers of matrix with diamondor some other super abrasive particle disposed therein is that thelayers are easily formed into other desirable shapes for the cutting,drilling, grinding, etc., segment. For example, FIG. 7A shows aperspective view of a segment, generally indicate at 30, of a superabrasive tool formed by a plurality of arcuate, longitudinal layers ofmatrix support material which are attached to one another to form athree-dimensional super abrasive member which has been infiltrated withthe braze to thereby hold the diamond within the matrix material of themember. The segment 30 is formed from first, second and third layers,34, 36 and 38, which are each arcuate. When the three are joinedtogether, an arcuate segment 30 is created. Such a segment, of course,may be used on cutting tools, which are non linear, and on other typesof tools for which a nonlinear superabrasive segment is desired. Becausethe layers 34, 36 and 38 are initially formed independent of oneanother, they are much easier to conform to a desired shape, and areable to do so while the brazed diamond particles 20 disposed therein areheld in their predetermined positions.

Each of the layers is impregnated with a plurality of superabrasiveparticles 20, typically diamond or cubic boron nitride. Because eachlayer is a relatively thin layer of metal matrix, (i.e., the metalmatrix will usually be no more than two times the thickness of thediameter of the particles), superior control over placement of thesuperabrasive particles in the metal matrix layer can be easilyachieved. As discussed above, the random placement of superabrasives inabrasive tools in the current art often lead to ineffective use ofsuperabrasive particles. By controlling distribution of superabrasivesthe present invention enables either even distribution which preventsunder or over spacing, or controlled distribution so that differentportions of the segment have different sizes and concentrations whichare matched to prevent traditional wear patterns.

Referring now to FIG. 7B, there is shown a cross-sectional view of aplurality of the layers 34, 36 and 38 of the segment 30. Of course, theconfiguration of the diamond particles may be used with the segmentshown in FIG. 6A or that shown in FIG. 7A. Unlike the embodiment of FIG.6B, the layers are each provided with the same size and concentration ofthe diamond particles 20. However, because the spacing is substantiallyuniform, there is no under spacing or over spacing between thesuperabrasive particles, and the segment 30 wears more evenly than thesegments of the prior art with randomly spaced particles. The more evenwear prevents premature failure of the segment 30, and thus extends thelife of the tool while keeping the amount of superabrasive used to aminimum. Furthermore, the braze which bonds to the diamond particles andthe matrix further strengthens each layer and prevents loss of thediamond particles.

FIG. 8 shows another possible embodiment of a segment 50 made inaccordance with the teachings of the present invention. The layeredstructure in a diamond segment may also be assembled transversely orhorizontally, and the braze may be applied to every layer, or to selectlayers as shown in FIG. 8. Thus, the segment 50 in FIG. 8 is formed froma plurality of transverse layers, generally indicated at 54. A firstplurality of the layers (i.e. the first four layers), indicated at 56,are provided with a first concentration of diamond particles 20 whichare brazed to bond to the matrix support material. A second plurality oflayers (i.e. the remaining 9 layers), indicated at 58, are provided witha second concentration, less than the first concentration and are alsobrazed to bond to the matrix support material.

Many cutting tools are configured such that the cutting segment 50 isprovided with a lead edge which performs a majority of the cutting andwhich receives most of the impact force when contacting the surface tobe cut. For example, a circular saw blade will usually have a pluralityof teeth or segments, each tooth having a leading edge, which takes theforce of the cutting. Because the leading edge performs a significantportion of the cutting, it is much more susceptible to wear than arerotationally rearward portions of the tooth. When formed in accordancewith the prior art, the teeth, however, often had relatively consistentabrasive disposed thereon. Over time the leading edge wearssignificantly, but the other portions coated with diamond particles aresubjected to minimal wear. Eventually, the abrasive is worn off theleading edge, while significant amounts remain on the other portions ofeach tooth. Thus, a considerable amount of super abrasive is wasted whenthe blade is discarded. The embodiment of FIG. 8 is specificallyconfigured to overcome such concerns. The layers 56 and 58 areconfigured to provide substantially even wear across the cutting segment50 by placing a larger percentage of the diamond particles 20 near theleading edge 56, than on rotationally distal portions 58. Thus, by thetime the leading edge has reached the end of its useful life, theremaining portions of the cutting segment 50 have also been worn out.Such controlled distribution of the superabrasive particles 20 decreasesthe use of the expensive material and lowers the cost for making thecutting segment 50 without hurting performance. Additionally, byproviding more ever wear, the cutting segment 50 will often be able tomaintain most of its cutting speed until shortly before the end of itsuseful life. Additionally, brazing the diamond particles 20 in layers 56and 58 further extends tool life.

FIG. 9 shows yet another layout of a segment wherein a three-dimensionalsuper abrasive member is formed with progressively denser abrasivedistribution toward the upper surface of a tool with horizontal layers.As with the embodiment of FIG. 8, the controlled distribution of thediamond particles 20 forms an improved abrasive segment 70, while at thesame time decreasing the cost of abrasive tools by decreasing theunnecessary consumption of diamond particles. Additionally, brazing maybe used on some of the layers, while being omitted from other layers, tothereby customize the abrasive segment 70.

With routine experimentation and the teachings of the method of thepresent invention, those skilled in the art will be able to customizecutting, drilling, grinding, polishing and other types of abrasivesegments which are specifically formed to maximize their abrasiveability (i.e. cutting, drilling, grinding, etc.) over an extended usefullife, while simultaneously decreasing the amount of super abrasive whichis used to form the tool in accordance with the principles of the methodof the present invention.

Referring now to FIGS. 10A through 10D, there is shown one method forforming layers in accordance with the principles of the presentinvention. Many of the same principles may be applied with respect tothe formation of layered segments as to the formation of segmentsdescribed in connection with FIGS. 1 through 5 above. The first step ofthe method is to form a sheet 100 of matrix support material 104 whichwill be bonded to the super abrasive particles 20. The sheet 100 ofmatrix support material 104 can be formed from conventional powders suchas cobalt, nickel, iron, copper, bronze, or any other suitable bondingagents. Additionally, for reasons, which are discussed in detail below,it is highly advantageous to use coarse powders, such as those above 34microns (400 mesh) in diameter. While the use of coarse powders isinconsistent with the current teachings that it is desirable to use thefinest powder available, considerable benefits may be achieved bycombining course powder and braze to secure diamond particles in place.

Once the sheet 100 of matrix support material 104 is formed, a template110 is laid on the top of the sheet as shown in FIG. 10A. The template110 contains apertures 114 that are larger than one abrasive particle20, but smaller than two abrasive particles, thereby allowing a singleparticle of the abrasive to be disposed at each specific location. Thethickness of the template is preferably between ⅓ to ⅔ of the height ofthe average abrasive particle 20. However, other thicknesses may be usedif appropriate accommodations are made for seating the abrasiveparticles in the desired locations.

After the template 110 is properly positioned, a layer of abrasiveparticles 20 is then spread over the template so that each aperture 114receives an abrasive particle. Those particles not falling into theapertures 114 in the template 110 are removed by tilting the substrate,sweeping the template with a broom, or some other similar method.

As shown in FIG. 10B, a generally flat surface 120, such as a steelplate, is then laid over the particles 20, which rest in the apertures114 in the template 110. The flat surface 120 presses the abrasiveparticles 20 at least partially into the pliable sheet 100 of matrixsupport material 104 to seat the particles.

After removing the template 110, the flat surface 120 is used again topress the abrasive particles 120 firmly into the sheet 100 of matrixsupport material 104 as shown in FIG. 10C. While the flat surface 120 ispreferable, those skilled in the art will appreciate that there may beoccasions when it is desirable to have some of the abrasive particles 20extend outwardly from the sheet 100 of matrix support material more thatother abrasive particles. In such situations, a contoured or otherwiseshaped surface could be used to seat some of the abrasive particles 20deeper into the sheet 100 of matrix support material 104, than otherparticles.

The sheets 100 may be first assembled to form the precursor of the toolsegment and then hardened and finished using the infiltration andsintering techniques set forth above, or they can be hardened andfinished individually, and subsequently assembled and combined to formthe tool segment or the entire tool body where appropriate. Typically,the assembly of the sheets 100 is accomplished by a known method such ascold compaction with a press. The “green” body so formed can then beconsolidated to form a final tool product by sintering or infiltrationas described above.

If desired, the process shown in FIGS. 10A through 10C can be repeatedon the other side of the sheet 100 of matrix support material 104 (asshown in FIG. 10D), to form an impregnated layer having diamondparticles 20 distributed throughout the layer in some predetermined,desired pattern. The process is typically repeated several times toobtain multiple thin layers or sheets 100, which are impregnated withthe diamond particles 20. Of course, each sheet 100 need not have thesame distribution pattern for the diamond particles 20, nor need theconcentration of the abrasive particles be the same in each sheet.

While the method described in FIGS. 10A through 10D is preferred formany applications, there are instances where it is desirable to have theabrasive particles 20 extend outwardly from the sheet 100 of matrixsupport material. For example, some tools may only have one layer ofabrasive. This can be accomplished simply by leaving the template 110 inplace when performing the steps shown in FIGS. 10A and 10B, and notfurther pressing the particles 20 into the matrix support material oncethe template has been removed.

In the alternative, FIGS. 11A through 11C show a side view of analternate to the method discussed in FIGS. 10A through 10D. The sheet130 of matrix support material 134 in FIGS. 11A through 11C is formed tobe of a lesser thickness than the cross-sectional thickness or diameteror the superabrasive particles 20. When the particles are pressed intothe sheet 130, the thickness of the sheet forces the superabrasiveparticles 20 to protrude from the matrix support material 134. The sheet130 is then infiltrated with diamond braze in the manner discussedabove.

While the spacing of apertures of the template shown in FIG. 11A through11C is generally uniform, according to one aspect of the invention, suchspacing need not be uniform, and can be according to any desiredpattern. As such, variations in spacing can be provided to facilitatedifferent concentrations on various portions to facilitate differentconcentrations on various portions of the sheet 130 of matrix material134. Likewise, by controlling the size of the apertures and the order inwhich the diamond particles are placed in the apertures, a single layercould be provided with particles of different sizes.

In yet another alternative, FIGS. 12A through 12C show a side view of amethod of forming superabrasive containing layers using sheets ofamorphous braze alloy. Again, in a similar manner as previouslydiscussed, FIG. 12A shows a template 110 having a plurality of apertures114 arranged in a predetermined pattern, which is placed on a thinsubstrate or sheet of matrix support material 107. The superabrasiveparticles 20 are then placed in the apertures and fixed in position withan adhesive or the like. As before, the flat surface may be contoured toaccommodate various tool configurations. The template 114 may then beremoved. A sheet of amorphous brazing alloy 106 is then placed over thesuperabrasive particles 20 as shown in FIG. 12B to form a single layersegment 15. In an alternative embodiment, the sheet of amorphous brazingalloy 106 may be placed on the substrate or matrix support materiallayer prior to placement of the superabrasive particles thereon.

Several single layer segments 15 may then be formed and combined into asingle multi-layered precursor 18, or green body, as shown in FIG. 12C.The single layer segments 15 may be secured using an adhesive as in thediscussion of FIGS. 6A through 6D or brazed using a traditional (i.e.does not necessarily contain a carbide former) brazing alloy. Thisprecursor may be formed of layers of uniform distribution ofsuperabrasive grits similar to FIG. 7B or of varying configurations,concentrations and/or particle size as in FIG. 6B. The method of thepresent invention includes configurations in which some of the layersare void of superabrasive particles altogether. Further, the matrixsupport material 107 may be a layer of metal or an unsintered metalpowder as described above. The resulting tool segment would havedifferent properties depending on which type of support material ischosen.

The precursor 18 is then placed in a vacuum furnace and heated to asufficient temperature to cause the sheet of amorphous braze alloy 106to melt and bond to the superabrasive particles 20 and to the layer ofmetal 107 to form a melded multi-layered tool having the desired patternof superabrasive particles distributed throughout as shown in FIG. 13.FIG. 13 shows a consolidated superabrasive tool segment 19 wherein thesuperabrasive particles 20 are arranged in a predeterminedthree-dimensional pattern. The areas identified by 108 and 109illustrate generally the layers of metal and braze alloy, respectively.The dotted lines are for illustrative purposes only and those skilled inthe art will recognize that the actual final tool segment may differ.For example, if the sheet of braze alloy is thinner than the diameter ofthe particles and the metal layer is solid during the consolidationprocess the final tool may have empty voids between particles. Further,if the layer of metal is formed of unsintered powder the consolidationprocess will cause the final tool to be much more homogenous due toinfiltration of the brazing alloy throughout the metal powder. Thethickness of the layer of metal 107 and the sheet of braze alloy 106 maybe of varying thickness. The thickness of the layer of metal 107 and/orthe sheet of brazing alloy may be less than the diameter of thesuperabrasive particles 20, as shown in FIG. 12A or either may bethicker than the diameter of the superabrasive particles used.

During the heating process the precursor assembly is heated to just overthe liquidus temperature to allow the braze alloy to flow somewhat.Maintaining the braze alloy, and the matrix or metal layer, near theliquidus temperature helps to prevent substantial movement of theparticles from their intended positions. Typically, a temperature ofabout 5° C. above the liquidus temperature over a relatively shortperiod of time, about 10 to about 20 minutes, is sufficient to obtainthe desired results.

EXAMPLES Example 1

40/50 mesh diamond grit (SDA-85+ made by De Beers Company) were mixedwith iron powders and an organic binder to form a mixture with diamondconcentration of 20 (5% of total value). The mixture was cold pressed ina steel mold to form the shape of a saw segment. The precursor wasplaced in a graphite mold and overlaid with a powder of Nicrobraz LM.The mold was heated under vacuum to about 1,050° C. for 20 minutes. Theinfiltrated braze had bonded diamond and matrix powder together for forma segment. Twenty-four of such segments were manufactured and they weretrimmed to desirable tolerances. These segments were brazed onto a14-inch round steel circular saw blade. The blade was used to cutgranite at a faster cutting rate than was possible with conventionaldiamond saw blades. Additionally, the brazed saw blades had a longeruseful life than a conventional diamond saw blade.

Example 2

40/50 mesh diamond grit (SDA-85⁺ made by De Beers Company) were mixedwith metal powder to form a mixture with a diamond concentration of 20(5% of total volume). Five different proportions of cobalt (about 1.5micrometer in size) and bronze (about 20 micrometers in size) were usedfor the matrix powder. An acrylic binder was added (8% by weight) to themixture and the charge was blended to form a cake. The cake was thenrolled between two stainless steel rollers to form sheets with athickness of 1 mm. These sheets were cut in the shape of saw segmentswith a length of 40 mm and width of 15 mm Three each of such segmentswere assembled and placed into a typical graphite mold for makingconventional diamond saw segments. The assembled segments were pressedand heated by passing electric current through the graphite mold. Aftersintering for three minutes, the segments were consolidated to a heightof 9 mm with less then 1% porosity. Twenty-four segments for eachcomposition were fabricated. They were brazed onto a circular saw of 14inches in diameter. These five blades were used for cutting granites andfound to perform equal or better than those with higher diamondconcentrations (e.g. 23) made by conventional methods. Microscopicexamination of the worn segment indicated that although diamondparticles were not planted into the layered matrix, they weredistributed more evenly than segments prepared by the traditionalmethod. The segregation of particles in a layered matrix wasconsiderably less than that in the thick body of conventional segments.

Example 3

The same procedures were followed as Example 2, but with 8 thinnerlayers (0.4 mm) for each segment. The diamond concentration was reducedto 15 and particles were positively planted according to theillustration as shown in FIGS. 10A through 10D. The diamond distributionwas much improved. As a result, the performance of these blades wereequal or better than those made by conventional methods with diamondconcentration of 20.

Example 4

Iron powders of about 100 mesh were mixed with an S-binder made by WallColmonoy Company to form a cake. The cake was then rolled to form sheetsof 0.4 mm in thickness. 40/50 mesh SDA-100⁺ diamond grit was positivelyplanted into these sheets to attain a concentration of 15. These diamondcontaining sheets were cut in the shape of saw segments with a length of40 mm and width of 9 mm. Eight of such segments were assembled as agroup and placed in a graphite mold. Twenty-four groups were placedhorizontally, and another twenty-four groups were placed vertically inthe graphite mold. Nicrobraz LM powder (−140 mesh) (made by WallColmonoy Company) was added on the top of these segments. These sampleswere heated in a vacuum furnace (10⁻⁵ torr) to 1050° C. for 20 minutesfor horizontally placed segments, and 30 minutes for vertically placedsegments. The melted LM alloy (Ni—Cr—B—Si with a liquidus point at 1000°C.) infiltrated into these segments and filled the porosity. The excessLM braze on these segments were ground by electrode discharge (EDG).Each of the 24 segments so fabricated were brazed onto a 14 inch(diameter) circular saw blade. These blades were used to cut granite andshowed marked improvement over conventional saw blades.

Example 5

Nicrobraz LM powder was mixed with an acrylic binder and rolled to formlayers of about 0.25 mm. 40/50 mesh MBS-960 diamond grit manufactured byGeneral Electric Company was positively planted into these metal layersaccording to the method as illustrated in FIG. 10A through 10D. Thesediamond planted metal layers were cut in proper size and wrapped around2,000 beads (pearls) of wire saw. These beads (10 mm in diameter by 10mm long) were divided into two groups; one contains 280 crystals (about0.2 carat). These beads were heated in a vacuum furnace to a temperatureof 1,000° C. for 8 minutes. These beads were mounted on several wiresaws and were used to cut marble, serpentine and granite. Theperformance of these beads was found to be superior to conventionalbeads. The latter beads were typically made by either hot pressing orelectroplating. These conventional beads may contain a much higheramount of diamond (up to 1 carat) per bead.

Example 6

The same method as described by Example 5, but applied to otherproducts, e.g., circular saws, thin-wall core bits, and curvaturegrounder. Each of these products shows superior performance overconventional electro-plated diamond tools having similar superabrasiveconcentrations.

Example 7

Mixture of metal powders that contain 87 wt % of −140 mesh Nicrobraz LM(made by Wall Colmonoy, U.S.), 8 wt % of iron of −125 mesh, and 5 wt %of copper of −60 mesh were mixed with 3 wt % of an acrylic binder toform a dough. The dough is rolled between two rollers to form sheets of0.6 mm thick. Each sheet is cut to shape and covered with a template.30/40 mesh (0.420 to 0.595 mm) diamond grits of SDA-100+ grade (made byDe Beers, South Africa) were positively planted into the metal layers ina predetermined pattern with a diamond-to-diamond distance of about 2mm. Three layers were stacked together and wrapped around a steel sleeveto form a diamond bead of 10 mm in diameter and 10 mm in length. Thesebeads were heated in a vacuum furnace to consolidate the metal and alsobraze the diamond in place and onto the steel sleeve. 1,000 of suchdiamond beads were fitted over 5 mm steel cable that contained 7×19wires, and they are spaced by plastic coating formed by injectionmolding. The wire was 25 meters long and it was joined end-to-end toform a loop. This wire saw was used to cut granite blocks (3.5 meterlong by 1.8 meter high) of all grades. The life achieved was 0.5 squaremeter cut surface per diamond bead consumed (0.5 carat). This area cutis twice of that cut by conventional diamond beads made by a powdermetallurgical method.

Example 8

This is the same as example 7, except many diamond impregnated layerswere assembled to form a block of 20 mm long by 5 mm thick by 7 mm high.These blocks were consolidated in a vacuum furnace to form diamondsegments. Each segment contained about 8 volume percent diamond. 30 ofsuch segments were brazed onto a 4 meter long steel frame and the famewas mounted on a reciprocating sawing machine. The saw was used to cutmarble blocks with a life more than twice longer than conventionaldiamond segments produced by powder metallurgical methods.

Example 9

This is the same as example 8, except the diamond planted layers wereassembled to form segments of about 24 mm long by 3.5 mm thick for acore bits of 150 mm in diameter. The diamond content in these segmentswas about 4 V %. 10 of such core bits were used to drill concrete. Thedrilling speed and the life of these core bits were much higher thanconventional diamond segments made by powder metallurgical methods.

Example 10

This is the same as example 9, except the shape of segments is forcircular saws. These segments were brazed to make circular saws of 230mm (with 18 segments of 40 mm by 8.5 mm by 2.4 mm), 300 mm (with 21segments of 50 mm by 8.5 mm by 2.8 mm), and 350 mm (with 24 segments of50 mm by 8.5 mm by 3.2 mm) in diameter. These saws were used to cutgranite, asphalt, and concrete with superior performance.

Example 11

This is the same as Example 8, except the segments are used as dressersfor conditioning grinding wheels.

Example 12

A single layer of 14/16 mesh (1.4 mm to 1.2 mm in size) diamond grits(natural diamond EMB-S made by De Beers) positively planted sheet iscovered over a pellet of 20 mm diameter by 8 mm thickness. Many of thesepallets were brazed in a vacuum furnace. More than 3000 of such palletswere mounted on floor grinding machines to grind stone and wood floors.The results indicate that the grinding speed could be three times fasterthan conventional diamond grinders.

Example 13

A single layer that contained positively planted diamond grits of 40/50mesh (0.420-0.297 mm size) ISD 1700 grade (made by Iljin Diamond ofKorea) was laid over the curved surface of a profile wheel and brazed toform a rigid tool in a vacuum furnace. More than 100 of such profilewheels of various diameters were used to form the edges of granite andmarble slabs. These profile wheels were capable to cut more than 3 timesfaster than conventional diamond tools made by either electroplating orsintering method.

Example 14

This is the same as example 13, except that the diamond planted layer iswrapped around a steel sleeve to form a single layered diamond beads.More than 100,000 of such beads were manufactured. They were used to cutgranite or marble with superior performance.

Example 15

This is the same as example 12, except the diamond grits were 80/100mesh, and the diamond planted layer was used to cover the surface of aflat disk of 4 inches in diameter. 4 such disks were produced and usedas conditioner to dress the CMP (chemical and mechanical polishing) padthat polished silicon wafers. The result indicated that the CMPefficiency was much improved and the conditioner outlasted conventionalconditioners made by either electroplating or brazing.

Example 16

Wall Colmonoy's Nicrobraz LM powder is used as the braze. It is mixedwith either iron powder (Fe), copper powder (Cu), or both in variousproportions (the following refer to the weight percentage of the overallmixture): 90LM/10SiC; 90LM/10WC; 100LM; 92LM/8Fe; 90LM/10Cu;82LM/8Fe/10Cu; 80LM/20Cu; 72LM/8Fe/20Cu; 70LM/30Cu; and 60LM/40Cu. Themixture also contains 4 weight percent of an acrylic binder that is usedto glue all powder together. The mixture is cold pressed to form a sheetand heated to 400° C. for 30 minutes in air to burn out most of theorganic binder. The preform is then placed in a vacuum oven maintainedat a pressure of 10⁻⁵ torn Heating is applied to a temperature of 1010°C. for 12 minutes. After the LM was completely melted and it infiltrated(or metal sintered by the aid of molten LM) the solid metal powder theconsolidated mass is cooled. After cooling the consolidated mass istaken out of the oven and tested for hardness and abrasion resistance.It was discovered that the HRB hardness for these compositions are 140,130, 120, 118, 116, 110, 108, 100, 100, and 70, respectively. Theabrasion resistance is decreases in the same order.

The hardness or abrasion resistance is important, as it must match thewear rate of diamonds in a tool so the grit can be exposed to the properheight for cutting a work piece efficiently. When an abrasive material,such as diamond particles, is bonded to a soft matrix it may become overexposed. As a result, the abrasive material may be shattered ordislodged during the cutting action thus reducing the tool life.

It has been determined based on these experiments that diamond bonded ona 92LM/8Fe matrix is most suitable to cut hard materials such asconcrete, granite, and sandstone. A 80LM/20Cu matrix is more suitable tocut softer materials such as limestone and marble.

Diamond grits of 30/40 mesh (SDA-100+ of De Beers Company) were mixedwith an 80LM/20Cu matrix. Various cutting tools containing 30concentration diamonds (about 8 volume percent) were produced. Toolsincluded circular saw segments, gang saw segments, and wire saw beadswhich were then brazed to circular saw blades, reciprocatively cuttinggang saw blades, and steel cables respectively. Although somewhatrandom, these tools were used to saw a variety of rocks with long livesand high cutting rates.

Example 17

This is an example of sintering solid braze powder together without themelting step. LM powder was mixed with either Fe, Cu, or both in variousproportions and an acrylic binder (4 weight percent) to form a dough.The dough is then rolled using steel rollers to form sheets 1 mm thick.30/40 (18 concentration) and 40/50 (22 concentration) diamond grits ofSDA-100+ were positively planted into these sheets using a template thatcontained holes of proper size in fixed positions. These sheets were cutto a size of 40 mm long by 8 mm wide. Five of these cut sheets werestacked together with three center layers that contained 30/40 meshdiamond. The assembly was hot pressed in a graphite mold at 400 atm and900° C. After cooling, the segments were brazed onto circular steelblades. The blades with matrices containing 80LM/20Cu and 80LM/10Fe/10Cuperformed satisfactorily.

Example 18

In this example single layer diamond forms are brazed directly onto thesubstrate for making a pad conditioner. LM powder is mixed with 4 weightpercent of acrylic binder to form a malleable dough. The dough is rolledbetween two steel rolls to form a layer 0.2 mm thick. 80/90 mesh diamondgrits of IMD-H as manufactured by Iljin Diamond Company was used toplant into the sheet. The planting was guided by a template that fixedthe diamond to diamond distance as 0.7 mm. The diamond planted LM layeris then trimmed in size and glued using an organic binder to a flatstainless (316) plate 6.5 mm thick. The assembly is then heated invacuum to 1010° C. for 10 minutes. The heating caused the LM to melt andbond to the substrate. The finished diamond disk is used as a padconditioner that dressed the pad during the chemical and mechanicalplanarization (CMP) of silicon wafers. The result indicates that suchdiamond disk can double the life when compared to a conventional diamonddisk that contains randomly distributed diamond grits.

Example 19

This is the same as Example 18, except the Nicrobraz LM powder is 140mesh.

Example 20

Nicrobraz LM powder of 325 mesh is mixed with Nicrobraz S binder to forma slurry. The slurry is then sprayed onto 100 round stainless steelpallets of 20 mm in diameter and 8 mm thickness to form a thin coating.The spraying process was repeated until a thickness of 0.15 mm wasachieved. After the coating is dried, a template with holes drilled toform a square grid with a distance of 0.5 mm between holes is placed onthe substrate. 100/120 mesh diamonds are then placed on the substrate toform the predetermined grid pattern. The template is then removedleaving the diamond particles adhered to the surface. The binder is thenremoved by heating in an oven in air at 200° C. for 2 hours. Theassembly is then heated in a vacuum to 1,005° C. for 10 minutes. Duringthis process, the molten braze has wetted the diamond and capillaryforce has pulled down the diamond particles to touch the substrate. Theresults are diamond pallets with diamond firmly brazed to form a wettingslope and these diamond crystals form a predetermined pattern of grid.The resulting tool is well suited for use in CMP applications.

Example 21

This is the same as example 12, except that the slurry is a ready madeproduct supplied by Wall Colmonoy as NICRO-SPRAY.

Example 22

This is the same as example 12, except the slurry is prepared bysuspending NICROBRAZ LN powder in a methanol benzene solution containingNanbau resin (manufactured in Taiwan).

Example 23

The braze is provided as a sheet of amorphous braze alloy manufacturedby Honeywell as MBF-20 foil about 0.001″ thick. Various sizes arepunched out of the foil and glued to round stainless steel substrate. Atemplate is then used to arrange 80/90 mesh diamond particles in apredetermined grid pattern. The assembly is then dewaxed and heated in avacuum furnace to melt the alloy and bond the diamond to the substrate.The final tool is used as a pad conditioner for CMP applications. Theresulting tool demonstrates that the polishing rate can be sustainedmuch longer than conventional pad conditioners. Further, defects on thesemiconductor wafers is greatly reduced.

Example 24

The braze is provided as a sheet of amorphous braze alloy manufacturedby Honeywell as MBF-20 foil, having a thickness of 0.002″. Annularsections 100 mm in diameter having 50 mm holes at the center are punchedout of the foil. A template is then placed on the annular ring ofamorphous braze and 60/80 mesh diamond particles are sprinkled over thetemplate surface. The excess diamonds are removed and then the templateis removed leaving the diamonds particles set in a predeterminedpattern. An additional annular ring is glued on the top of these diamondparticles. Six of such amorphous alloy-diamond amorphous alloysandwiches are assembled with a stainless ring of the same size but witha thickness of 0.1 mm between every two of such layers. An acrylicadhesive is used to glue the assembly together. The final assembly isthen heated to 200° C. for 2 hours to drive off the adhesive. Theassembly is then heated in a vacuum furnace at 1,005° C. for 15 minutes.The resulting tool is a three dimensional structure that contains adiamond array not just on surface but also in volume. This threedimensional structure is then mounted to a chuck with a shaft for use asa grinding wheel. Such a grinding wheel has the unique feature ofcontaining connected pores around diamond. These pores can serve asrunways for removing cutting debris. The openness of this grinding wheelmakes it free cutting so the cutting speed is twice that of conventionalgrinding wheels. Conventional grinding wheels using metal as matrixcontains no such interconnected pores.

A distinct advantage cutting tools of the present invention have overthe prior art cutting tools lies in the manner in which the tool may beused. Diamond saws are typically made in the form of a circular bladethat cuts the workpiece by rotation in the same direction with eachrotation. This one directional movement causes a “tail” to be formed,wherein the matrix material rotationally forward of the diamond particleis worn away, but the matrix material behind the diamond particle isprotected by the diamond particle. If the saw rotation were to bereversed, the diamond particle would easily be knocked free of thematrix.

Round saws, however, can only cut the work piece to a depth of less thanone-half the diameter of the saw. In order to cut thicker workpieces, aframe or gang saw is typically used. Because these saws movereciprocally, the diamond particles must be securely held on each side.As a result, tails of diamond matrix cannot be maintained to hold thediamond particles in place. It is for this reason that reciprocatingdiamond saws have not been used to cut hard rock such as granite. Ratherthey are used to cut only soft materials such as marble.

This invention allows diamond to be held chemically by a braze. Hence,matrix tails are not needed to support the diamond. As a result, toolsmade according to the present invention can be used on reciprocatingsaws to cut hard materials. This breakthrough can expand diamondapplications to markets, which were previously unavailable due tolimitations of the prior art.

In addition to being able to improve the performance of the tool and toreduce the cost of manufacturing, this invention also provides an easiermethod for making thin bladed tools. For example, the electronicindustry requires using larger and larger silicon wafers (now 12 inchesin diameter). Hence, thinner saw blades for slicing silicon crystals,and thinner dicing wheels for grooving silicon chips with tighterpartitions have been in great demand.

Prior to the present invention, it has been extremely difficult to makevery thin tools that contain evenly distributed diamond particles. Thepresent invention provides an alternative method for making such tools.For example, it has been discovered that by mixing micron powders ofdiamond, a blend of metal powders (e.g., bronze and cobalt) and asuitable binder, the material can be rolled to a thickness thinner than0.1 mm—a thickness which is thinner than most dicing wheels. By firingthis thin sheet and mounting it on a tool holder, a thin dicing wheelcan be made.

In the alternative to the above, it has been found in accordance withthe present invention that some of the advantages of the controlleddistribution, multilayered superabrasive configurations described abovecan be achieved without the use of a template. More specifically, theabrasive particles can also be mixed in with the matrix powder and madeas an ingredient of the layered sheet. In this case, the distribution ofabrasive particles is still somewhat random. Even so, their distributionis typically more uniform than that in a conventional abrasive body. Thesegregation of abrasive particles and matrix powders discussed in thebackground section is less extensive in a substantially two-dimensionalsheet than in a three-dimensional body. This is particularly true forsheets made by a deforming process (e.g., by rolling). In this case,abrasive particles are further spread out in the matrix by the shearingaction of the rollers.

This invention may also be applicable to other applications not relatedto making abrasive tools. For example, graphite or metal sheets plantedwith diamond particles may be used as seeds for diamond growth underhigh pressure and temperature. Industrial diamonds are typicallyproduced by compressing alternative layers of graphite and metalcatalyst (e.g., Fe, Co, or Ni alloy) to high pressure and heating abovethe melting point of the catalyst. Diamond will then nucleate randomlyon the interface of these layers. The quality of the diamond crystalformed often suffers by the impingement of growing crystals that aredistributed unevenly. Hence, the yield and cost of diamond synthesis canbe substantially improved by making the nuclei uniformly distributed.This invention can provide layers of either graphite or metal catalystwith a pre-determined pattern of diamond seeds. If organic binders areintroduced during the fabrication of these layers, they can be removedby heating in a furnace before loading into the press.

Thus, there is disclosed an improved method for making superabrasivetools with improved performance. The above description and examples areintended only to illustrate certain potential uses of this invention. Itwill be readily understood by those skilled in the art that the presentinvention is susceptible of a broad utility and applications. Manyembodiments and adaptations of the present invention other than thoseherein described, as well as many variations, modifications andequivalent arrangements will be apparent from or reasonably suggested bythe present invention and the forgoing description thereof withoutdeparting from the substance for scope of the present invention.Accordingly, while the present invention has been described herein indetail in relation to its preferred embodiment, it is to be understoodthat this disclosure is only illustrative and exemplary of the presentinvention and is made merely for purpose of providing a full andenabling disclosure of the invention. The forgoing disclosure is notintended or to be construed to limit the present invention or otherwiseto exclude any such other embodiment, adaptations, variations,modifications and equivalent arrangements, the present invention beinglimited only by the claims appended hereto and the equivalents thereof.

It is to be understood that the above-referenced arrangements areillustrative of the application for the principles of the presentinvention. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of the present invention and the appended claims are intendedto cover such modifications and arrangements. Thus, while the presentinvention has been described above with particularity and detail inconnection with what is presently deemed to be the most practical andpreferred embodiments of the invention, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function,manner of operation, assembly, and use may be made without departingfrom the invention as set forth in the claims.

What is claimed is:
 1. A method for making a CMP pad dresser,comprising: arranging a plurality of superabrasive particles on a 4 inchdiameter flat disk in a metal matrix comprising a brazing alloy sheet atspecific positions such that the plurality of superabrasive particlesare held in the brazing alloy sheet according to a predeterminedpattern, wherein tips of each of the plurality of the superabrasiveparticles protrude from the brazing alloy sheet to a uniform heighthaving a variance that is less than or equal to 50 μm, saidsuperabrasive particles being disposed in different sizes and/ordifferent concentrations at different parts of the brazing alloy sheet,and wherein the plurality of superabrasive particles is positioned inthe predetermined pattern at a first location and the predeterminedpattern of the plurality of superabrasive particles is transferred to asecond location on the brazing alloy sheet in order to be held in thebrazing alloy sheet.
 2. The method of claim 1, wherein arranging theplurality of superabrasive particles includes: placing a template havinga plurality of apertures corresponding to the predetermined pattern at afirst location upon a transfer plate; filling the apertures withsuperabrasive particles; removing the template from the transfer plate;and transferring the superabrasive particles to the brazing alloy sheetat the second location using the transfer plate such that thesuperabrasive particles are arranged in the predetermined pattern. 3.The method of claim 2, wherein the template is configured to hold onlyone superabrasive particle in each aperture.
 4. The method of claim 2,further comprising affixing the superabrasive particles to the transferplate with an adhesive.
 5. The method of claim 1, wherein the uniformheight is an equal height.
 6. The method of claim 1, wherein thepredetermined pattern is a uniform pattern.
 7. The method of claim 1,wherein the plurality of superabrasive particles is diamond or cBN. 8.The method of claim 1, wherein the plurality of superabrasive particlesis diamond.
 9. A method for making a CMP pad dresser, comprising:forming a metal matrix comprising a brazing alloy sheet on a 4 inchdiameter flat disk to hold a plurality of superabrasive particlestherein; placing a template having a plurality of aperturescorresponding to a predetermined pattern upon a transfer plate at afirst location; filling the apertures with superabrasive particles;removing the template from the transfer plate; and transferring thesuperabrasive particles to a second location, said second location beingon the brazing alloy sheet, using the transfer plate such that thesuperabrasive particles are arranged in the predetermined pattern in thebrazing alloy sheet, wherein tips of each of the plurality of thesuperabrasive particles protrude from the brazing alloy sheet to auniform height having a variance that is less than or equal to 50 μm,and wherein the plurality of superabrasive particles are disposed indifferent sizes and/or different concentrations at different parts ofthe brazing alloy sheet.
 10. The method of claim 9, wherein the uniformheight is an equal height.
 11. The method of claim 9, wherein thetemplate is configured to hold only one superabrasive particle in eachaperture.
 12. The method of claim 9, wherein the predetermined patternis a uniform pattern.
 13. The method of claim 9, wherein the pluralityof superabrasive particles is diamond or cBN.
 14. The method of claim 9,wherein the plurality of superabrasive particles is diamond.
 15. Themethod of claim 9, further comprising affixing the superabrasiveparticles to the transfer plate with an adhesive.
 16. The method ofclaim 15, further comprising applying a secondary adhesive at the secondlocation, wherein the secondary adhesive bonds to the superabrasiveparticles more strongly than the adhesive.
 17. The method of claim 9,wherein the transfer plate is transparent.
 18. A CMP pad dresser madeaccording to the method of claim 9.